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Year 8 Science — Speed and motion

Work out speed, distance or time from the other two, choose between m/s and km/h, and tell uniform linear motion from non-uniform.

Name: ________________________

Before you start

A train leaves station A and reaches station D. Its position along the straight track is marked out below.

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Read the marks as the position of a train at equal intervals of time. When each gap between successive positions matches the one before, the speed is not changing and the motion is uniform. When the gaps grow or shrink, the speed is changing and the motion is non-uniform.

  1. 1.A car's journey is 60 kilometres and it takes 1 hour, so its speed works out at 60 kilometres per hour. But it stopped twice at signals. What does the chapter call the 60?

    • a) Its lowest speed
    • b) Its uniform speed
    • c) Its average speed
    • d) Its highest speed

  2. 2.Match each instrument on a vehicle's dashboard to what it tells the driver.

    • Speedometer
    • Odometer
    • shows how fast the vehicle is going right now
    • shows how far the vehicle has travelled altogether

  3. 3.Sort each stretch of a train's journey along a straight track.

    Groups: Uniform linear motion · Non-uniform linear motion

    • A train pulling out of a station and picking up speed
    • A train covering different distances in successive ten-minute intervals
    • A train slowing down as it comes into a station
    • A train running at an unchanging speed along a straight stretch
    • A train covering the same distance in each ten-minute interval

  4. 4.A cyclist covers 240 metres in 30 seconds. What is the cyclist's speed in metres per second? Answer with a number.

  5. 5.A train is moving at 72 kilometres per hour. What is that speed in metres per second? Answer with a number.

  6. 6.The chapter calls uniform linear motion an idealisation. Why?

    • a) Objects are seldom found holding a constant speed for long, which is why average speeds are used
    • b) It applies to trains but to nothing else
    • c) Speed cannot be measured accurately enough to check it
    • d) Straight tracks do not exist in practice

  7. 7.A train travels at a speed of 90 kilometres per hour. How many hours does it take to cover 360 kilometres? Answer with a number.

  8. 8.Three sprinters are part-way through a race on a straight track and one of them is ahead of the others. What does that tell you?

    • a) She started before the others did
    • b) She has a longer stride, which is a different thing from speed
    • c) She has covered more distance in the same time, so she is the faster
    • d) Nothing until the race is over

Answer key — Year 8 Science — Speed and motion

  1. 1. c) Its average speed
  2. 2. Speedometer → shows how fast the vehicle is going right now; Odometer → shows how far the vehicle has travelled altogether
  3. 3. A train covering the same distance in each ten-minute interval → Uniform linear motion; A train running at an unchanging speed along a straight stretch → Uniform linear motion; A train covering different distances in successive ten-minute intervals → Non-uniform linear motion; A train pulling out of a station and picking up speed → Non-uniform linear motion; A train slowing down as it comes into a station → Non-uniform linear motion
  4. 4. 8
  5. 5. 20
  6. 6. a) Objects are seldom found holding a constant speed for long, which is why average speeds are used
  7. 7. 4
  8. 8. c) She has covered more distance in the same time, so she is the faster