Me

Speed, velocity and acceleration Edexcel International GCSE Science (Double Award) revision

Not started

Learn it

In plain words

Speed is how far you go each second. Acceleration is how quickly your speed changes: a car that goes from 0 to 20 m/s in 5 s gains 4 m/s every second, so its acceleration is 4 m/s².

Three things to know

  1. Average speed = total distance ÷ total time. Velocity is speed in a stated direction.
  2. Acceleration = change in velocity ÷ time taken. Its unit is m/s². Slowing down is a negative acceleration.
  3. Near the Earth's surface a falling object with no air resistance accelerates at about 9.8 m/s².

Worked example

A cyclist speeds up from 4 m/s to 10 m/s in 3 s. Find the acceleration.

  1. Change in velocity = 10 − 4 = 6 m/s.
  2. Acceleration = change in velocity ÷ time = 6 ÷ 3.
  3. = 2 m/s².

Tips and tricks

  • Write the formula first, then put the numbers in, then give the answer with its unit. Even with a slip in the arithmetic, the formula and the substitution usually earn marks.
  • Slowing down is a negative acceleration. Don't lose the minus sign.
6 questions, about 2 minutes.

It lands in your notebook with its questions as flashcards.

Speed, velocity and acceleration: 6 questions and answers

These are the quiz’s questions. Do the quiz first, then come back here for the ones that got you.

  1. A car travels 150 km in 2.5 hours. What is its average speed?
    • 37.5 km/h
    • 60 km/h (the answer)
    • 152.5 km/h
    • 375 km/h

    150 ÷ 2.5 = 60 km/h.

  2. What does an acceleration of 3 m/s² mean?
    • The object moves 3 m every second.
    • The velocity changes by 3 m/s every second. (the answer)
    • The object takes 3 s to travel 1 m.
    • The speed is 3 m/s.

    Acceleration is the change in velocity each second.

  3. A ball is dropped from rest and falls freely for 2.0 s. Taking g as 9.8 m/s², what is its speed?
    • 4.9 m/s
    • 9.8 m/s
    • 19.6 m/s (the answer)
    • 39.2 m/s

    Speed gained = acceleration × time = 9.8 × 2.0.

  4. A bus slows from 20 m/s to 5 m/s in 5 s. What is its acceleration?
    • −3 m/s² (the answer)
    • −4 m/s²
    • 3 m/s²
    • 5 m/s²

    (5 − 20) ÷ 5 = −3 m/s². The minus sign shows it is slowing down.

  5. What is the difference between speed and velocity?
    • Velocity is measured in different units.
    • Speed is always greater than velocity.
    • Velocity includes direction. (the answer)
    • Speed includes direction.

    Velocity is speed in a given direction, so it is a vector.

  6. A sprinter runs 100 m in 12.5 s. What is her average speed?
    • 0.125 m/s
    • 1.25 m/s
    • 8.0 m/s (the answer)
    • 12.5 m/s

    100 ÷ 12.5 = 8.0 m/s.

Things you can type

Or go straight to

Or browse a shelf