MYP Physics: Speed, Velocity & Acceleration — Answered

Answer these questions by identifying whether you need a scalar (speed) or vector (velocity, acceleration) quantity, then apply the matching formula with matching units. Show working line by line — distance/time, displacement/time, or (final minus initial velocity)/time — because MYP Criterion C rewards clear, logical processing, not just a final number.

Speed tells you how fast something is moving; velocity tells you how fast and in which direction. Speed is a scalar — just a magnitude, like 20 m/s — while velocity is a vector, like 20 m/s north. A car doing laps at a constant speed still has changing velocity, because its direction keeps changing.

Acceleration measures how quickly velocity changes over time — speeding up, slowing down, and changing direction all count as acceleration. The formula is a = (v − u) ÷ t, where v is final velocity, u is initial velocity and t is time. A positive result means speeding up; a negative result means decelerating.

For MYP 4-5 Physics you need three core formulas: speed = distance ÷ time, velocity = displacement ÷ time, and acceleration = change in velocity ÷ time, written a = (v − u) ÷ t. You should also know that the gradient of a distance-time graph gives speed, and the gradient of a velocity-time graph gives acceleration.

Most marks disappear for three reasons: mixing up speed and velocity in a written explanation, forgetting or misusing units, and rounding too early in a multi-step calculation. Examiners marking Criterion C want the formula written out, correct substitution shown, and a final answer with the right unit — skip any one step and the process mark goes, even if the number is correct.

Average speed equals total distance divided by total time, using the same units throughout — metres and seconds, or kilometres and hours, never mixed. If a runner covers 120 m in 15 s, average speed = 120 ÷ 15 = 8 m/s. Always check your units before you calculate, not after you've written the answer.

On a distance-time graph, the gradient at any point equals speed — a straight line means constant speed, a curve means changing speed, and a flat line means the object is stationary. On a velocity-time graph, the gradient equals acceleration, and the area under the line equals distance travelled.

In MYP 4-5, these questions are mostly assessed under Criterion A (Knowing and Understanding) for definitions, formula use and calculations, and Criterion C (Processing and Evaluating) when you're analysing data from a motion experiment, such as a trolley on a ramp. Some schools also draw on Criterion B if students design the investigation themselves.

Speed, velocity and acceleration typically appear in MYP Year 4 or 5, depending on how a school sequences its Sciences curriculum — most introduce it once students can confidently rearrange equations and interpret graphs, usually alongside forces and Newton's laws in the same unit of work.

No — MYP 4-5 kinematics is the foundation, not the hard part. DP Physics builds on the same speed-velocity-acceleration ideas but adds proper vector treatment, and at HL, motion graphs analysed with calculus-style reasoning and the full set of uniformly-accelerated-motion equations that MYP doesn't require.

MYP 4-5 kinematics builds the exact vocabulary and formula habits your child needs for DP Physics Topic 2 (Mechanics, first examined under the current 2025 Physics guide), where speed, velocity and acceleration questions become properly vector-based and combine with forces and energy. Students who nail units and sign conventions now find DP kinematics far less of a jump.

Improvement comes down to three habits: writing the formula before substituting numbers, checking units every time, and working through past worksheet questions until the process feels automatic. Most students stuck at a mid-range Criterion C level are skipping the working-out step, not genuinely misunderstanding the physics.

Look for resources that pair short revision notes with topic-specific practice questions and full mark schemes, so your child can see exactly how marks are awarded for the working, not just the final answer. Worksheets that isolate speed, velocity and acceleration questions — separate from forces or energy — build formula fluency before topics get mixed together in a test.