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Energy Forms and Transfer — Free MYP3 Sciences Practice Questions
1QuestionClosed Systems and Energy AccountingConcept Practice
3 marks~5 minCriterion B
A pendulum, a bouncing ball, a skateboard on a ramp, and a mass on a spring are each treated as a closed system. The table below shows energy values recorded for each system.
System — Initial (J) — at lowest point (J) — Final (J)
System — Initial (J) — at lowest point (J) — Final (J)
| Pendulum | 10.0 | 10.0 | 10.0 |
|---|---|---|---|
| Bouncing ball | 8.0 | 8.0 | 8.0 |
| Skateboard ramp | 12.0 | 12.0 | 12.0 |
| Mass on spring | 6.0 | 6.0 | 6.0 |
a
State what you notice about the three energy values recorded for any one system. [1]
b
Explain what these values show about the total mechanical energy of a closed system. [1]
c
Describe the energy transformations that occur as the pendulum moves from its highest point to its lowest point and back to its highest point, and explain why the final equals the initial . [1]
Solutions
2QuestionClosed Systems and Energy AccountingConcept Practice
2 marks~3 minCriterion A
A sealed flask is completely filled with water. A heating coil and a thermometer are inserted through the stopper. No water or air can enter or leave the flask. When the heating coil is switched on, the thermometer reading rises.
Identify the energy store that increases in the water as the temperature rises, and state where in the system this energy is stored. [2]
Identify the energy store that increases in the water as the temperature rises, and state where in the system this energy is stored. [2]
Solutions
3QuestionComparing the Three Modes of Heat TransferConcept Practice
3 marks~5 minCriterion B
A student investigates which metal heats up fastest in hot water. She places equal-sized rods of copper, aluminium, and iron into separate containers, each holding the same volume of water at the same starting temperature. She records the temperature of each rod every minute for 5 minutes.
a
Identify the independent variable in this investigation. [1]
b
Identify the dependent variable and explain why it is measured every minute rather than only at the end of 5 minutes. [1]
c
The copper rod reaches 48 °C after 3 minutes, while the iron rod reaches only 39 °C. Suggest one reason, in terms of heat transfer, why copper heats up faster than iron. [1]
Solutions
4QuestionComparing the Three Modes of Heat TransferConcept Practice
2 marks~3 minCriterion A
A person stands near a campfire on a still evening. No wind is blowing, and the person is not touching the fire.
a
Identify the method of heat transfer that allows the person to feel warmth from the campfire. [1]
b
Explain how this method of heat transfer allows energy to travel from the fire to the person. [1]
Solutions
5QuestionComparing Energy Resources for SustainabilityConcept Practice
2 marks~3 minCriterion A
The diagram shows a simplified solar panel. Component A is one of several identical units arranged in rows across the top surface of the panel.
a
Identify component A. [1]
b
Explain why multiple units of component A are connected together in a solar panel. [1]
Solutions
6QuestionCalculating Efficiency PercentConcept Practice
2 marks~3 minCriterion A
A hair dryer receives of electrical energy. It produces of heat energy and of sound energy.
Using the terms input energy, useful output, and wasted energy, describe how electrical energy is transformed as it passes through the hair dryer. [2]
Using the terms input energy, useful output, and wasted energy, describe how electrical energy is transformed as it passes through the hair dryer. [2]
Solutions
7QuestionKinetic and Potential EnergyConcept Practice
3 marks~5 minCriterion B
A bowling ball rolls along a lane at a constant speed of . The kinetic energy of balls with different masses is shown below.
Use .
| Mass (kg) | 4 | 5 | 6 | 7 |
|---|---|---|---|---|
| Kinetic energy (J) | 50 | 62.5 | 75 | 87.5 |
Use .
a
Calculate the kinetic energy of a bowling ball of mass travelling at . [1]
b
Explain why kinetic energy increases as mass increases, even though speed stays the same. [1]
c
Analyse the data in the table. Describe the relationship between mass and kinetic energy, and use numerical evidence to support your answer. [1]
Solutions
8QuestionDefinition and Examples of Different Energy TypesConcept Practice
2 marks~3 minCriterion A
The diagram below shows a battery connected to a lit light bulb.
Identify the energy type stored in the battery. [1]
Explain the energy conversion that occurs when the circuit is switched on. [1]
Identify the energy type stored in the battery. [1]
Explain the energy conversion that occurs when the circuit is switched on. [1]
Solutions
9QuestionEnergy Conversion from One Form to AnotherConcept Practice
6 marks~9 minCriterion A
A battery-powered flashlight contains a battery, a switch, and a light bulb. A student measures that the battery supplies 6 J of energy. The light bulb converts 4 J into light energy and the remaining energy into heat.
a
Identify the form of energy stored in the battery. [1]
b
Describe the sequence of energy transformations that occur from the moment the switch is closed until the bulb produces light. [2]
c
Using the energy values given, explain how the heat produced by the bulb supports the idea that energy is conserved. [3]
Solutions
10QuestionClosed Systems and Energy AccountingAssessment Practice
3 marks~5 minCriterion C
A student uses a small solar panel to charge a phone battery. The solar panel receives 500 J of solar energy. The battery stores 180 J as electrical energy. The remaining energy is transferred to the surroundings as heat.
a
Calculate the energy transferred to the surroundings as heat. [1]
b
Explain one reason why the actual heat lost to the surroundings may differ from your answer in part (a). [1]
c
The student claims this solar charger is "about 35% efficient." Justify whether this claim is correct, using your answer from part (a). [1]
Solutions
11QuestionDesigning Simple Energy InvestigationsAssessment Practice
5 marks~8 minCriterion D
A student builds a simple solar oven from a cardboard box lined with aluminium foil and covered with plastic wrap. She places 200 mL of water at an initial temperature of inside the oven and records the temperature every 5 minutes for 30 minutes on a sunny day.
a
Identify and explain two limitations of this solar oven as a model for a real solar cooker. [3]
b
Propose one modification to reduce heat loss and explain how it would make the model more representative of a real solar cooker. [2]
Solutions
12QuestionComparing the Three Modes of Heat TransferAssessment Practice
12 marks~18 minCriterion C
Three identical boxes are insulated with cotton, wool, or aluminium foil. A heat lamp is placed equidistant from each box. Temperature inside each box is recorded every 5 minutes.
| Time (min) | 0 | 5 | 10 | 15 | 20 |
|---|---|---|---|---|---|
| Cotton (°C) | 20 | 25 | 29 | 32 | 34 |
| Wool (°C) | 20 | 23 | 26 | 28 | 29 |
| Foil (°C) | 20 | 35 | 50 | 62 | 72 |
a
Identify which box has the smallest temperature increase between 0 and 20 minutes, and calculate that total increase. [2]
b
Explain why wool reduces heat transfer more effectively than cotton, using the concepts of conduction and convection. [4]
c
Analyse the data for all three materials and justify which box will have the lowest temperature at 30 minutes, using evidence from the table and your knowledge of heat transfer by radiation. [6]
Solutions
13QuestionComparing the Three Modes of Heat TransferAssessment Practice
12 marks~18 minCriterion D
A farmer grows plants in a greenhouse. The transparent glass walls allow sunlight to enter. During summer, the inside temperature can reach 45 °C on hot days; during winter, the outside temperature can drop to −5 °C at night.
a
Describe the role of each of the three modes of heat transfer — conduction, convection, and radiation — in heating the greenhouse interior. [3]
b
Explain one advantage of using a greenhouse to grow plants compared with growing them outdoors. [2]
c
Analyse how the greenhouse performs poorly in each of the two extreme conditions described: a summer day at 45 °C and a winter night at −5 °C. For each condition, identify the problem and explain why the greenhouse structure alone cannot solve it. [7]
Solutions
14QuestionDefinition of Non-Renewable ResourcesAssessment Practice
12 marks~18 minCriterion C
The graph below shows atmospheric CO2 concentration (in parts per million, ppm) from 1960 to 2020. The table below provides additional data.
Fossil fuel — Formation time — CO2 emitted per unit of energy (g/kWh)
Fossil fuel — Formation time — CO2 emitted per unit of energy (g/kWh)
| Coal | ~300 million years | 820 |
|---|---|---|
| Oil | ~100 million years | 650 |
| Natural gas | ~50 million years | 490 |
a
Describe the trend in atmospheric CO2 concentration shown in the graph between 1960 and 2020. [2]
b
Explain why fossil fuels are classified as non-renewable resources, using the formation time data provided. [4]
c
A country is deciding whether to replace its coal power plants with natural gas power plants. Using the data in the table, analyse whether this change would reduce CO2 emissions, and explain how continued use of either fuel contributes to the greenhouse effect. [6]
Solutions
15QuestionComparing Energy Resources for SustainabilityAssessment Practice
8 marks~12 minCriterion D
A coal-fired power plant and a solar farm each produce 500 kWh of electricity per day. The coal plant burns coal continuously; the solar farm uses 2 000 panels spread across 4 hectares of land.
a
Describe what happens chemically when coal is burned to produce electricity, and identify one harmful substance released into the atmosphere. [2]
b
Explain why the solar farm requires 4 hectares of land to match the coal plant's daily output of 500 kWh. [2]
c
A town council must choose one energy source for the next 30 years. Using the information above, analyse the environmental impacts of each source and justify which source the council should choose. [4]
Solutions
16QuestionDefinition of Non-Renewable ResourcesAssessment Practice
12 marks~18 minCriterion B
The graph shows the projected oil extraction rate (billions of barrels per year) and global population (billions of people) from 2020 to 2070. The extraction rate starts at 35 billion barrels/year in 2020, peaks at 45 billion barrels/year in 2040, then falls to 10 billion barrels/year in 2070. The population rises steadily from 7.8 billion to 9.8 billion over the same period.
a
Using the graph, identify the year in which the oil extraction rate reaches its peak, and state what happens to the extraction rate after that year. [2]
b
Explain how the definition of a non-renewable resource accounts for the decline in the oil extraction rate shown in the graph. [4]
c
Analyse two factors, not shown in the graph, that could cause the actual year when oil supply fails to meet global demand to be either earlier or later than the graph suggests. For each factor, state whether it would make the shortage happen sooner or later, and why. [6]
Solutions
17QuestionCalculating Efficiency PercentAssessment Practice
8 marks~12 minCriterion D
A school is replacing 200 old bulbs (each 60 W, 10% efficient) with 200 LED bulbs (each 12 W, 80% efficient). The bulbs operate for 5 hours each day. Electricity costs 0.15 USD per kilowatt-hour (kWh).
a
Calculate the useful power output of one old bulb and one LED bulb. [2]
b
Calculate the daily electricity cost of running all 200 old bulbs and all 200 LED bulbs. [3]
c
A student claims: "The LED bulbs are the better choice because they are more efficient." Using the data above and one factor beyond efficiency, analyse whether this claim is fully supported. [3]
Solutions
18QuestionCalculating Efficiency PercentAssessment Practice
3 marks~5 minCriterion C
The graph below shows how the efficiency of an electric kettle changes as the volume of water inside it increases.
a
Describe the trend shown in the graph. [1]
b
Explain why efficiency is lower when the volume of water is small. Use the concept of heat loss to the surroundings in your answer. [1]
c
The graph shows that efficiency levels off at large volumes. Analyse why increasing the volume further produces little additional change in efficiency. [1]
Solutions
19QuestionCalculating Efficiency PercentAssessment Practice
6 marks~9 minCriterion B
A solar panel receives of light energy and produces of useful electrical energy. The remaining energy is lost as heat.
The table below shows the efficiency of three solar panels at different light intensities.
The table below shows the efficiency of three solar panels at different light intensities.
| Light intensity () | 200 | 500 | 800 |
|---|---|---|---|
| Panel A efficiency (\%) | 30 | 36 | 34 |
| Panel B efficiency (\%) | 25 | 32 | 38 |
| Panel C efficiency (\%) | 28 | 36 | 30 |
a
Calculate the efficiency of the solar panel described above. [2]
b
Calculate the average efficiency of all three panels at each light intensity and identify which light intensity gives the highest average efficiency. [2]
c
Analyse the data in the table to describe the relationship between light intensity and solar panel efficiency. [2]
Solutions
20QuestionDefinition and Examples of Different Energy TypesAssessment Practice
12 marks~18 minCriterion D
A family is considering installing solar panels on their roof to heat water. They live in a location where sunlight hours vary significantly across the year. In summer, the panels receive an average of 8 hours of sunlight per day; in winter, only 2 hours per day. The family requires hot water every day of the year.
a
Identify one advantage of using solar panels to heat water. [1]
b
Explain two limitations of using solar panels for this family's hot water supply, given the variation in sunlight hours. [4]
c
The family is considering adding an insulated storage tank and a gas-powered backup heater to their system. Analyse how these two additions would work together to provide a reliable hot water supply throughout the year. [7]
Solutions
21QuestionEnergy in Daily Life ApplicationsAssessment Practice
6 marks~9 minCriterion C
A hair dryer draws 1200 W from a wall socket. Its heating element warms the air, and its motor drives a fan to blow that air outward. Of the total electrical energy input, 75% is converted to thermal energy and 20% to kinetic energy.
a
Identify the form of energy that enters the hair dryer. [1]
b
Explain how the hair dryer converts electrical energy into two different output forms. [3]
c
A student claims the hair dryer converts 100% of its electrical energy into useful output. Using the percentages given, analyse whether this claim is correct. [2]
Solutions
22QuestionEnergy Conversion from One Form to AnotherAssessment Practice
12 marks~18 minCriterion B
A student tests a solar panel over five days, recording sunlight intensity and electrical energy output.
| Sunlight Intensity (W/m²) | 200 | 400 | 600 | 800 | 1000 |
|---|---|---|---|---|---|
| Electrical Energy Output (W/m²) | 40 | 100 | 180 | 280 | 400 |
a
Calculate the efficiency of the solar panel for each of the five days. Show your working. [5]
b
Describe the relationship between sunlight intensity and efficiency, using values from your calculations to support your answer. [3]
c
On Day 6, the sunlight intensity is 900 W/m². Analyse the data to deduce the electrical energy output for this day. Show your reasoning. [4]
Solutions
23QuestionEnergy Changes in Everyday DevicesAssessment Practice
8 marks~12 minCriterion D
A hybrid car captures energy during braking and stores it in a battery. A gasoline car does not. The table below shows data for two cars travelling the same route.
| Car type | Energy input (kJ): 1000 |
|---|---|
| Gasoline car | Useful mechanical energy output (kJ): 250 |
| Hybrid car | Useful mechanical energy output (kJ): 380 |
a
Describe the sequence of energy transformations that occurs in a gasoline car as it moves along a road. [2]
b
Explain why the hybrid car produces less waste heat than the gasoline car, using the data in the table to support your answer. [3]
c
A city council claims that switching its entire bus fleet to hybrid vehicles will solve its air-pollution and resource-use problems. Using evidence from the table and your knowledge of hybrid technology, analyse whether this claim is fully justified. [3]
Solutions
24QuestionEnergy Changes in Everyday DevicesAssessment Practice
12 marks~18 minCriterion C
A hybrid car uses both a gasoline engine and an electric motor. During braking, regenerative braking converts the car's kinetic energy back into electrical energy, which is stored in the battery. A conventional gasoline car wastes this energy as heat.
a
Describe the energy transformations that occur when the hybrid car accelerates from rest using the electric motor only. [2]
b
Explain one environmental advantage of a hybrid car over a conventional gasoline car. [2]
c
A student claims: "Regenerative braking makes a hybrid car more efficient than a conventional car because no energy is wasted during braking."
Analyse this claim. In your answer, explain how regenerative braking improves efficiency and assess whether the student's claim is fully correct. [8]
Analyse this claim. In your answer, explain how regenerative braking improves efficiency and assess whether the student's claim is fully correct. [8]
Solutions