Forces and Motion — Free IB MYP5 Physics Questions

1QuestionCalculating Weight Using W = mgConcept Practice

2 marks~3 minCriterion D

A conservation biologist rescues a sea turtle and uses a spring scale to weigh it on Earth, where gravity is 9.8 N/kg. The scale reads 490 N. The same scale is then taken to the Moon, where gravity is 1.6 N/kg.

a

Calculate the mass of the turtle. [1 mark]

b

Calculate the weight of the turtle on the Moon. [1 mark]

c

Outline ONE environmental impact of misjudging the turtle's weight when planning its transport by plane from the Moon back to Earth. [1 mark]

Solutions

2QuestionWeightlessness and Orbiting ObjectsConcept Practice

2 marks~3 minCriterion A

A weather satellite orbits Earth at an altitude where gravitational field strength is

5.7 \ \text{N kg}^{-1}

.

a

State the force that keeps the satellite in its circular orbit. [1]

b

The satellite has a mass of

800 \ \text{kg}

. Calculate the gravitational force acting on it at this altitude. [1]

Solutions

3QuestionGravitational Field Strength on Earth and Other PlanetsConcept Practice

4 marks~6 minCriterion C

A robotic probe is sent to the Moon, where the gravitational field strength is

g = 1.6 \text{ N/kg}

. A field-line diagram of the Moon's gravitational field is provided for reference. On Earth,

g = 10 \text{ N/kg}

.

a

State what the direction of gravitational field lines around a planetary body indicates. [1]

b

Describe how the spacing of gravitational field lines is related to the strength of the gravitational field, referring to both closely spaced and widely spaced lines. [2]

c

Justify why the Moon's gravitational field-line diagram shows a lower density of field lines than an equivalent diagram for Earth, using the values of

g

given above. [1]

Solutions

4QuestionCalculating Weight Using W = mgConcept Practice

2 marks~3 minCriterion B

Outline the steps you would take to investigate the relationship between mass and weight using a spring balance and a set of masses. The diagram shows a spring balance with a 1.0 kg mass attached, reading 9.8 N. Include in your outline the measurements you would record and how you would present your data.

Solutions

5QuestionTerminal Velocity in Free Fall - Basic LevelConcept Practice

2 marks~3 minCriterion B

A student drops a ball bearing into a tall cylinder filled with glycerine. The diagram shows the setup.

Outline the steps of the experiment to determine how the velocity of the ball bearing changes as it falls through the glycerine.

Solutions

6QuestionApplications in Engineering and SportsConcept Practice

2 marks~3 minCriterion A

A skydiver falls at terminal velocity. The diagram shows two force arrows acting on the skydiver: arrow A points upward and arrow B points downward.

a

Identify the force represented by arrow A and explain why it acts in the direction shown. [1]

b

Identify the force represented by arrow B and explain why it acts in the direction shown. [1]

Solutions

7QuestionTerminal Velocity in Free Fall - Basic LevelConcept Practice

2 marks~3 minCriterion C

The graph below shows the velocity of a skydiver during freefall, from the moment they jump out of the plane until they reach the ground.

Describe the motion of the skydiver, explaining the changes in velocity and acceleration at different stages of the fall. Use appropriate scientific terminology.

Solutions

8QuestionForce Diagrams and Vector RepresentationConcept Practice

2 marks~3 minCriterion A

A 0.80 kg book rests motionless on a horizontal table. The diagram shows two forces acting on the book: a downward weight of

7.8 \text{ N}

and an upward normal force of

7.8 \text{ N}

.

a

Identify the two forces shown in the diagram, stating the direction and magnitude of each. [1]

b

Explain why the book remains stationary, referring to Newton's first law and the net force acting on the book. [1]

Solutions

9QuestionLaw of conservation of momentumConcept Practice

2 marks~3 minCriterion D

During a spacewalk, an astronaut of mass 80 kg drifts away from the International Space Station. To return, she briefly fires a thruster pistol, expelling gas backwards.

Explain how the law of conservation of momentum allows the astronaut to move towards the station. [1]

Identify one societal impact of applying conservation of momentum in human spaceflight. [1]

Solutions

10QuestionNewtons Third Law Action and Reaction PairsConcept Practice

2 marks~3 minCriterion C

During a rocket launch, the engines expel exhaust gases at high speed.

a

State the SI unit for force. [1]

b

A student claims: "The exhaust gases push the rocket upward, but the rocket does not push back on the gases." Using Newton's third law, explain why this claim is incorrect and identify the action–reaction force pair responsible for the rocket's upward acceleration. [1]

Solutions

11QuestionCentral of mass and stability of objectsConcept Practice

2 marks~3 minCriterion A

Double-decker buses have a high passenger deck, raising the centre of mass significantly above the road surface.

Identify one design feature engineers use to lower the centre of mass of a double-decker bus. [1]

Explain how this feature reduces the risk of the bus tipping over when cornering. [1]

Solutions

12QuestionCircular Motions ExamplesConcept Practice

2 marks~3 minCriterion A

A car of mass 1200 kg travels at a constant speed of 15 m/s around a flat, circular curve of radius 50 m. The centripetal force is provided entirely by friction between the tyres and the road.

Calculate the centripetal force acting on the car. [2]

Solutions

13QuestionCentripetal and Centrifugal ForcesConcept Practice

2 marks~3 minCriterion A

A car travels at constant speed around a flat, circular track of radius 45 m. The only horizontal force acting on the car is the contact force between the tyres and the road surface.

a

Identify the specific type of horizontal force that acts on the car and state the direction in which it acts. [1]

b

The car's mass is 1200 kg and its speed is 15 m s

^{-1}

. Calculate the magnitude of this force. [1]

Solutions

14QuestionGravitational Field Strength on Earth and Other PlanetsAssessment Practice

4 marks~6 minCriterion B

Two planets, P and Q, have the same mass but different radii. Planet P has a smaller radius than Planet Q. Gravitational field-line diagrams for both planets are provided.

G = 6.67 \times 10^{-11} \text{ N m}^2 \text{ kg}^{-2}

Planet P	mass $= 6.0 \times 10^{24}$ kg	radius $= 6.4 \times 10^{6}$ m
Planet Q	mass $= 6.0 \times 10^{24}$ kg	radius $= 1.3 \times 10^{7}$ m

a

Deduce which planet has the stronger surface gravitational field strength, using evidence from the field-line diagrams. [1]

b

Show that the surface gravitational field strength of Planet P is approximately

9.8 \text{ N kg}^{-1}

, using

g = \dfrac{GM}{r^2}

. [1]

c

Analyse how reducing a planet's radius while keeping its mass constant affects its surface gravitational field strength. Use

g = \dfrac{GM}{r^2}

and your results from (a) and (b) to support your answer. [2]

Solutions

15QuestionCalculating Weight Using W = mgAssessment Practice

10 marks~15 minCriterion D

A mining company uses highly sensitive gravimeters to detect underground ore deposits by measuring minute differences in gravitational acceleration caused by variations in subsurface density. During a survey, a gravimeter records a local gravitational acceleration of

9.800 \, 047 \, \text{m s}^{-2}

, compared to the regional average of

9.800 \, 000 \, \text{m s}^{-2}

. The gravimeter can resolve differences as small as

1 \times 10^{-6} \, \text{m s}^{-2}

.

a

Calculate the difference in weight of a

500 \, \text{kg}

reference mass between the anomaly location and the regional average. [2]

b

Explain how a gravimeter survey could be used to identify a buried deposit of gold ore, given that gold has a significantly higher density than the surrounding granite bedrock. [3]

c

Evaluate whether the economic benefits of extracting a newly discovered mineral deposit justify the environmental costs, considering habitat destruction, water pollution, and greenhouse gas emissions from mining operations. [5]

Solutions

16QuestionTerminal Velocity in Free Fall - Basic LevelAssessment Practice

4 marks~6 minCriterion B

A student drops spheres of the same size and shape but different masses and measures their terminal velocities. The experimental setup consists of a tall clear tube, a release mechanism at the top, and a motion sensor at the bottom. The motion sensor measures the time taken for the sphere to fall a certain distance, from which the terminal velocity is calculated. The diagram shows a sphere falling through the tube.

The following data was collected:

Mass of Sphere (g): 10 20 30
Terminal Velocity (m/s): 4.5 6.4 7.8

a

Investigate the pattern in the data. What relationship do you observe between the mass of the sphere and its terminal velocity? [2 marks]

b

Predict the terminal velocity of a sphere with a mass of 40 g. [2 marks]

c

Justify your prediction in part (b) based on the pattern you identified in part (a). Explain your reasoning. [2 marks]

Solutions

17QuestionAir Resistance and StreamliningAssessment Practice

10 marks~15 minCriterion A

Two identical spheres, each of mass

0.5 \, \text{kg}

, are dropped simultaneously from rest at high altitude. Sphere A has a smooth surface; Sphere B has a rough surface. Both experience significant air resistance (

g = 9.8 \, \text{m/s}^2

). The velocity–time graph shows each sphere accelerating until it reaches terminal velocity: Sphere A at

55 \, \text{m/s}

, Sphere B at

40 \, \text{m/s}

.

a

Calculate the drag force acting on Sphere A at its terminal velocity. [2]

b

Deduce the drag force acting on Sphere B at its terminal velocity, and explain why your answer is the same as in part (a) despite the two spheres reaching different terminal velocities. [3]

c

The drag force on a sphere is given by

F_d = \frac{1}{2} C_d \rho A v^2

, where

C_d

is the drag coefficient,

\rho

is air density,

A

is cross-sectional area, and

v

is speed. Using this equation and your results from parts (a) and (b), analyse how the rough surface of Sphere B produces a lower terminal velocity than the smooth surface of Sphere A. [5]

Solutions

18QuestionAir Resistance and StreamliningAssessment Practice

4 marks~6 minCriterion D

Modern electric vehicles (EVs) are designed with carefully shaped body panels, sloped windscreens, and sealed underbodies to reduce air resistance at highway speeds.

a

Identify the physics term for the force that streamlining reduces, and state one specific design feature of an EV that minimises this force. [1]

b

Explain how the streamlined shape of an EV reduces air resistance compared with a non-streamlined vehicle. [1]

c

Discuss the societal and environmental impacts of streamlining in EV design, considering both benefits and limitations. [2]

Solutions

19QuestionAir Resistance and StreamliningAssessment Practice

12 marks~18 minCriterion D

A car manufacturer tests two electric vehicle body shapes — a teardrop and a boxy design — in a wind tunnel to minimise air resistance. Wind tunnel data show the teardrop shape produces a drag force of 120 N at 30 m s

^{-1}

, while the boxy shape produces 310 N at the same speed. The electric motor delivers a constant power output of 18 kW.

a

Explain how the teardrop shape reduces air resistance compared with the boxy shape. [3]

b

Using the drag force values, analyse how the difference in air resistance affects the energy available to propel each vehicle over a 10-minute journey at 30 m s

^{-1}

. [4]

c

Evaluate the limitations of wind tunnel testing in predicting the aerodynamic performance of a vehicle under real-world driving conditions. [5]

Solutions

20QuestionFriction Causes Effects and ReductionAssessment Practice

12 marks~18 minCriterion C

A toy car is released from rest at the top of a ramp and rolls onto a flat surface. Students measured the distance the car travelled and the temperature rise of its axles after each run across three surfaces. The car was released from the same height each time.

Distance travelled (m)	Carpet 0.4	Wood 1.1	Tile 1.8
Axle temperature rise (°C)	Carpet 4.2	Wood 2.1	Tile 0.7

a

Explain how the data provides evidence that friction converts kinetic energy into thermal energy. [3]

b

Analyse the relationship between surface texture and the amount of energy converted by friction, using values from the data. [4]

c

A student claims: "The total mechanical energy of the car is not conserved in this experiment, so the law of conservation of energy does not apply." Evaluate this claim, identifying one limitation of the experimental evidence that affects how confidently the claim can be assessed. [5]

Solutions

21QuestionTypes of Forces Contact and Non-ContactAssessment Practice

6 marks~9 minCriterion B

You are investigating how surface area affects air resistance. Paper cones of different diameters are dropped from a height of 2.0 m and the time taken to fall is recorded.

Diameter (cm)	10	15	20	25	30
Fall time (s)	1.2	1.5	1.9	2.4	3.0

a

Construct a graph of fall time (y-axis) against diameter (x-axis). Describe the pattern shown by your graph. [2]

b

Interpret the graph to predict the fall time for a cone of diameter 35 cm, and explain the reasoning behind your prediction. [2]

c

Analyse how increasing surface area affects the motion of a falling cone. In your answer, justify your conclusion using Newton's second law. [2]

Solutions

22QuestionCollisionsAssessment Practice

2 marks~3 minCriterion D

During a crash test, a 1500 kg car travelling at 15 m/s is brought to rest. Engineers compare two designs: a rigid frame (collision time 0.05 s) and a crumple-zone frame (collision time 0.25 s).

a

Explain how the crumple-zone design reduces the force experienced by passengers, referring to the impulse-momentum theorem

F = \dfrac{\Delta p}{\Delta t}

. [1]

b

Evaluate one societal benefit and one limitation of fitting crumple zones as standard in all new vehicles. [1]

Solutions

23QuestionForce Diagrams and Vector RepresentationAssessment Practice

6 marks~9 minCriterion C

A drone delivery package of mass 5.0 kg rests on a frictionless warehouse floor. Two horizontal cable tensions act on it simultaneously: 30 N directed due east and 20 N directed due north.

a

Construct a free-body diagram of the package. Label each force vector with its magnitude and direction. [1]

b

Calculate the magnitude of the net horizontal force acting on the package. [2]

c

The warehouse manager claims the package will accelerate at an angle of 45° north of east. Analyse this claim using your results from parts (a) and (b), and justify whether it is correct. [3]

Solutions

24QuestionForce Diagrams and Vector RepresentationAssessment Practice

5 marks~8 minCriterion D

A 2.0 kg block slides down a frictionless inclined plane set at three angles. A force sensor records the net force parallel to the incline. The theoretical model predicts

F_{\text{net}} = mg\sin\theta

, giving the dashed line on the graph.

Experimental data — Angle (

^\circ

): 10, 20, 30. Net force (N): 3.2, 6.0, 8.5.

Use

g = 9.8\ \text{m s}^{-2}

and

m = 2.0\ \text{kg}

.

a

Calculate the predicted net force at each angle. [2]

b

Determine the percentage difference between the experimental and predicted values at each angle, and identify whether any systematic pattern exists. [2]

c

Evaluate whether the theoretical model is valid, using the pattern in your percentage differences to justify your conclusion. [1]

Solutions

25QuestionCollisionsAssessment Practice

2 marks~3 minCriterion A

During a game of billiards, ball A (mass 170 g) strikes stationary ball B (mass 170 g). The diagram shows the collision: arrow

F_{AB}

points from ball A toward ball B, and arrow

F_{BA}

points from ball B toward ball A.

a

State which two forces form the Newton's Third Law action-reaction pair in this collision. [1]

b

Ball A decelerates at

6.0 \ \text{m s}^{-2}

during the collision. Deduce the magnitude and direction of the acceleration of ball B at the same instant. [1]

Solutions

26QuestionCalculating Net Force in One and Two DimensionsAssessment Practice

6 marks~9 minCriterion B

A student uses a force table to investigate how two perpendicular forces combine. Forces are applied to a central ring, and the resultant magnitude is measured. The recorded data are:

Force $F_1$ (N)	3	6	5	9
Force $F_2$ (N)	4	8	12	12
Resultant $R$ (N)	5	10	13	15

a

Analyse the data to deduce the mathematical relationship between

F_1

,

F_2

, and

R

. Support your answer with calculations from at least two data sets. [2]

b

Apply your relationship to predict the resultant force when perpendicular forces of 8 N and 15 N act on the ring. Show your substitution and result. [2]

c

A technician claims that doubling both perpendicular forces always doubles the resultant. Evaluate this claim using your relationship, and state whether the claim holds for all pairs of perpendicular forces or only for specific cases. [2]

Solutions

27QuestionCentral of mass and stability of objectsAssessment Practice

6 marks~9 minCriterion A

A rectangular wooden block of mass

5.0 \text{ kg}

, width

0.20 \text{ m}

, and height

0.40 \text{ m}

rests on a horizontal table. A horizontal force,

F

, is applied at the top edge of the block. Take

g = 9.8 \text{ m/s}^2

.

a

Calculate the weight of the block. [1]

b

Deduce the maximum horizontal force

F

that can be applied at the top edge before the block tips over. Show all working. [3]

c

The block is replaced with one of identical mass but greater height. Analyse how this change affects the maximum force required to tip the block, and explain what this implies about the stability of taller objects. [2]

Solutions

28QuestionCentral of mass and stability of objectsAssessment Practice

12 marks~18 minCriterion C

A rectangular wooden block of constant width

w = 5.0\ \text{cm}

is placed on an inclined plane. The incline angle is slowly increased until the block tips. This is repeated for blocks of different heights,

h

. The graph below shows tipping angle

\theta

(degrees) on the

y

-axis against height

h

(cm) on the

x

-axis. The curve passes through the point

(5.0,\ 45°)

and decreases as

h

increases.

a

Analyse the graph to describe the relationship between

h

and

\theta

. [2]

b

The tipping angle is known to follow

\theta = \arctan\!\left(\dfrac{w}{h}\right)

. Show that this formula is consistent with the point

(5.0,\ 45°)

on the graph, and use it to determine

\theta

when

h = 2.5\ \text{cm}

. [3]

c

Explain how the height of the block affects the position of its centre of mass and, in turn, its stability on the inclined plane. [3]

d

A student claims: "Doubling the width to $10.0\ \text{cm}$ while keeping $h = 5.0\ \text{cm}$ will double the tipping angle." Evaluate this claim using the formula

\theta = \arctan\!\left(\dfrac{w}{h}\right)

. [4]

Solutions

29QuestionIdentifying Balanced and Unbalanced Force ScenariosAssessment Practice

12 marks~18 minCriterion A

A 10 kg storage crate is pushed horizontally across a warehouse floor. Two horizontal forces act on it:

- Applied force

F_A = 50\ \text{N}

to the right
- Frictional force

F_f = 20\ \text{N}

to the left

The crate starts from rest.

a

Deduce the net horizontal force acting on the crate, including its direction. [2]

b

Calculate the acceleration of the crate during the first 3 seconds, stating the direction. [3]

c

Calculate the velocity of the crate at

t = 3\ \text{s}

. [3]

d

At

t = 3\ \text{s}

, the applied force is removed. Analyse how the motion of the crate changes, and justify your answer using Newton's laws and a calculation of the new acceleration. [4]

Solutions

30QuestionMotion of Objects Under Balanced ForcesAssessment Practice

12 marks~18 minCriterion D

A hovercraft moves at constant velocity across a calm lake. Its thrust engine produces a forward force of 1200 N. The air cushion reduces surface friction to near zero, but air resistance (drag) still acts on the craft.

a

Explain why the hovercraft moves at constant velocity even though the engine is running. [2]

b

The hovercraft then crosses from the lake onto a marshy shoreline. Explain how the forces acting on the hovercraft change during this transition, and describe the effect on its motion. [4]

c

A sudden crosswind exerts a lateral force of 400 N on the hovercraft. Evaluate whether the hovercraft can maintain its intended straight-line path, and discuss ONE environmental consequence of the engine response required. [6]

Solutions

31QuestionHooke's Law and turning effectAssessment Practice

9 marks~14 minCriterion C

A student investigates how four springs (A, B, C, D) stretch under applied forces by hanging masses and measuring extension with a ruler.

Spring A — Force (N): 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 | Extension (cm): 0.0, 2.5, 5.0, 7.5, 10.0, 12.5

Spring B — Force (N): 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 | Extension (cm): 0.0, 1.0, 4.0, 9.0, 16.0, 25.0

Spring C — Force (N): 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 | Extension (cm): 0.0, 3.0, 6.0, 9.0, 12.0, 15.0

Spring D — Force (N): 0.0, 1.0, 2.0, 3.0, 4.0, 5.0 | Extension (cm): 0.0, 1.5, 3.0, ?, 6.0, 7.5

a

Construct a graph of extension (cm) against force (N) for springs A, B, and C on the same axes. [3]

b

Identify which springs obey Hooke's law (

F = kx

) and explain, using your graph, why Spring B does not. [2]

c

Calculate the spring constant

k

(in N/cm) for Spring C. Show your working. [2]

d

Deduce the missing extension for Spring D at 3.0 N. Justify whether Spring D obeys Hooke's law, using both the completed data set and your findings from parts (b) and (c). [2]

Solutions

32QuestionHooke's Law and turning effectAssessment Practice

12 marks~18 minCriterion D

A sports-medicine engineer is designing a running blade prosthetic for a below-knee amputee. The blade is modelled as a spring with spring constant

k = 85 \ \text{N m}^{-1}

. During a stride, the blade compresses by

x = 0.040 \ \text{m}

under the athlete's weight.

Carbon-fibre blades cost approximately 15 000 dollars; polypropylene alternatives cost approximately 800 dollars but have a lower, less tunable

k

.

a

State Hooke's Law and calculate the restoring force the blade exerts during compression. [2]

b

Analyse how the choice of spring constant influences both the biomechanical performance and the manufacturing cost of a prosthetic running blade. [4]

c

Evaluate the ethical and environmental implications of the cost gap between carbon-fibre and polypropylene prosthetic blades, considering equity of access and the environmental impact of each material across its full lifecycle. [6]

---

Solutions

33QuestionInterpreting Distance-Time GraphsAssessment Practice

4 marks~6 minCriterion C

A cyclist's motion along a straight road is recorded and plotted as a distance–time graph. For the first 8 s, the line is straight, passing through (0, 0) and (8, 16). At

t = 8\ \text{s}

, the line becomes noticeably steeper and remains straight, reaching (18, 66) at the end of the journey.

a

Deduce the time at which the cyclist's speed changes, and state what feature of the graph supports this. [1]

b

Calculate the speed of the cyclist in each section, showing full working. [2]

c

Analyse how the distance–time graph would differ if the speed had increased gradually rather than suddenly, justifying your answer in terms of gradient. [1]

Solutions

34QuestionCalculating Speed from a GraphAssessment Practice

4 marks~6 minCriterion A

A cyclist accelerates from rest along a straight road. The distance-time graph for the first 8 s of the journey shows a smooth upward curve.

a

Deduce what the increasing gradient of the curve indicates about the cyclist's motion. [1]

b

A tangent drawn to the curve at

t = 4\ \text{s}

passes through the points

(2,\ 4)

and

(6,\ 36)

. Calculate the cyclist's instantaneous speed at

t = 4\ \text{s}

. [2]

c

Analyse why a tangent is required to find instantaneous speed from a curved distance-time graph, but not from a straight-line distance-time graph. [1]

Solutions

35QuestionCalculating Acceleration and Area Under GraphsAssessment Practice

4 marks~6 minCriterion A

A rocket launches from rest and reaches a speed of

600 \, \text{m/s}

in

30 \, \text{s}

with uniform acceleration.

a

Calculate the acceleration of the rocket during the launch. [1]

b

Deduce the distance travelled in the first

30 \, \text{s}

by finding the area under the speed-time graph. [1]

c

The rocket instead reaches

600 \, \text{m/s}

in

15 \, \text{s}

. Evaluate the effect of this change on both the acceleration and the distance travelled. Justify your answer with quantitative reasoning. [2]

Solutions

36QuestionCalculating Speed from a GraphAssessment Practice

6 marks~9 minCriterion C

A toy car accelerates from rest along a straight track. A motion sensor records the following data:

Time (s)	0.0	1.0	2.0	3.0	4.0	5.0
Distance (m)	0.0	0.5	2.0	4.5	8.0	12.5

a

Construct a distance–time graph for this data. Draw a smooth curve through all six points. [2]

b

Deduce the instantaneous speed of the car at

t = 3.0\ \text{s}

by drawing a tangent to the curve at that point. Show all working. [2]

c

The motion sensor has a resolution of

\pm 0.05\ \text{m}

. Analyse how this limitation affects the reliability of the instantaneous speed you deduced in (b), and suggest one way to reduce this effect. [2]

Solutions

37QuestionCalculating Acceleration and Area Under GraphsAssessment Practice

2 marks~3 minCriterion D

During a brake test, a car decelerates uniformly from

20 \ \text{m s}^{-1}

to rest in

4 \ \text{s}

.

a

State one way automotive engineers use the acceleration calculated from a velocity-time graph to improve vehicle safety. [1]

b

Justify why average acceleration alone may be insufficient for designing a reliable braking system. [1]

Solutions

38QuestionInterpreting Speed-Time GraphsAssessment Practice

2 marks~3 minCriterion B

The speed-time graph shows the motion of an object.

Segment 1	from (0	0) to (6	24)
Segment 2	from (6	24) to (10	8)

Time is in seconds (s) and speed is in metres per second (m/s).

a

[2 marks] Calculate the acceleration for each segment. Show your working.

b

[2 marks] Investigate the relationship between the sign of the slope and the type of motion (speeding up or slowing down). Generalize a rule that connects the slope direction to acceleration.

c

[2 marks] Predict the acceleration if the line segment had a slope of zero. Justify your prediction using your rule from part (b).

Solutions

39QuestionDescribing Motion Qualitatively and QuantitativelyAssessment Practice

8 marks~12 minCriterion D

A self-driving car is travelling at

20 \text{ m/s}

when a pedestrian steps into the road

60 \text{ m}

ahead. The car's sensor system has a reaction time of

0.2 \text{ s}

before braking begins. Two braking profiles are available: a smooth profile with constant deceleration

3.0 \text{ m/s}^2

, and an emergency profile with constant deceleration

8.0 \text{ m/s}^2

.

a

Calculate the total stopping distance for the smooth profile. Use

v^2 = u^2 + 2as

to find the braking distance. [2]

b

Calculate the total stopping distance for the emergency profile and deduce, with reference to your answers, which profile prevents a collision. [2]

c

Evaluate the ethical justification for a manufacturer programming the smooth profile as the default, considering how risk is distributed between passengers and pedestrians and how real-world conditions such as wet roads or sensor latency affect the reliability of the stopping-distance model. [4]

Solutions

40QuestionCircular Motions ExamplesAssessment Practice

4 marks~6 minCriterion B

A planet orbits a star in a circular path. The graph below shows orbital speed plotted against orbital radius for several planets in the same star system.

a

Deduce the relationship between orbital speed

v

and orbital radius

r

shown in the graph. [1]

b

A planet orbits at radius

r = 1.5 \times 10^{11}

m with orbital speed

v = 3.0 \times 10^{4}

m s

^{-1}

. Calculate its orbital period. [2]

c

Justify why a planet at half this orbital radius would have a shorter orbital period, referring to gravitational force, centripetal force, and orbital speed. [1]

Solutions

41QuestionCentripetal and Centrifugal ForcesAssessment Practice

4 marks~6 minCriterion A

A car of mass

m

travels at constant speed

v

around a circular track of radius

r

. A free body diagram showing the forces acting on the car is provided.

a

State the direction of the centripetal force acting on the car. [1]

b

The speed of the car is doubled while

r

remains constant. Deduce the new magnitude of the centripetal force in terms of the original force

F_c

. [1]

c

Analyse why centripetal force is necessary for circular motion, and explain what happens to the car's motion if this force is suddenly removed. [2]

Solutions

42QuestionCircular Motions ExamplesAssessment Practice

12 marks~18 minCriterion D

Gas centrifuges spin uranium hexafluoride (

\text{UF}_6

) at extremely high rotational speeds to separate

^{235}\text{U}

from

^{238}\text{U}

by mass difference. For nuclear power reactors,

^{235}\text{U}

must be enriched from its natural abundance of 0.7% to approximately 3–5%. The same centrifuge technology can, however, enrich

^{235}\text{U}

beyond 90% for weapons-grade material.

a

Explain why enriched uranium is necessary for sustaining a fission chain reaction in a commercial nuclear power reactor. [2]

b

Analyse the ethical concerns raised by the dual-use nature of gas centrifuge technology, considering both its role in civilian energy production and its potential for nuclear weapons development. [4]

c

Evaluate the environmental and long-term health risks associated with the full uranium fuel cycle — from mining through to radioactive waste disposal — and justify whether these risks make nuclear power an unacceptable energy source in the context of global climate change. [6]

Solutions

43QuestionCircular Motions ExamplesAssessment Practice

4 marks~6 minCriterion C

A passenger sits on the outer edge of a rotating fairground ride. At one instant, the ride completes a full circle of radius 4.0 m every 3.2 s. The passenger remains stationary relative to the seat throughout the ride.

a

Identify the force acting on the passenger that is directed toward the centre of rotation. [1]

b

The passenger reports feeling "pushed outward" during the ride. Explain which actual force is responsible for keeping the passenger in circular motion, and link this to the sensation described. [2]

c

Evaluate whether the centrifugal force experienced by the passenger is a real force. Justify your answer using the concept of an inertial reference frame. [1]

Solutions

44QuestionCentripetal and Centrifugal ForcesAssessment Practice

12 marks~18 minCriterion D

A space elevator is a proposed structure that would transport cargo from Earth's surface to geostationary orbit. A cable, anchored at the equator and held taut by Earth's rotation, would allow electric climbing vehicles to ascend to orbit. The cable must withstand enormous tension and would be made from ultra-high-strength materials such as carbon nanotubes. The structure would reach approximately 36 000 km, passing through the troposphere, stratosphere, and mesosphere before reaching geostationary orbit.

a

Explain the environmental costs associated with extracting and processing the large quantities of carbon nanotube material required for the cable. [3]

b

Analyse how the choice of energy source for the climbing vehicles affects the overall environmental impact of operating the space elevator. [4]

c

Evaluate the environmental consequences of a catastrophic cable failure, considering the physical behaviour of the falling cable, the regions of the atmosphere it would pass through, and the long-term ecological effects. [5]

Solutions

45QuestionCentripetal and Centrifugal ForcesAssessment Practice

4 marks~6 minCriterion C

A passenger sits on the outer edge of a rotating fairground ride. From the ground, an observer sees the passenger moving in a circle. The passenger, however, feels pushed outward against the ride's outer wall.

A free body diagram of the passenger is provided.

a

State what is meant by the term 'centrifugal force'. [1]

b

Explain why centrifugal force appears to act on the passenger but is not observed by the person watching from the ground. [2]

c

Evaluate whether centrifugal force should be considered a real force, using Newton's laws of motion to justify your reasoning. [1]

Solutions

Forces and Motion — Free MYP5 Physics Practice Questions