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Grade 7 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 runner covers 400 meters in 50 seconds. What is the runner's speed in meters per second? Answer with a number.

  2. 2.A bus moves at a speed of 50 kilometers per hour for 2 hours. How far does it go, in kilometers? Answer with a number.

  3. 3.A galloping horse reaches about 18 meters per second. A train is moving at 72 kilometers per hour. Which is faster?

    • a) They are the same speed in different units
    • b) The horse, because 18 is bigger than the train's speed once converted
    • c) The train, because 72 kilometers per hour is 20 meters per second
    • d) There is no way to compare them, because the units differ

  4. 4.A train covers 300 kilometers in 4 hours. What is its speed in kilometers per hour? Answer with a number.

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

  6. 6.Two trains are timed over the same hour. Train X covers 20 kilometers in each ten-minute interval. Train Y covers 20, then 15, then 25. Which is in uniform linear motion, and how do you know?

    • a) Train Y, because its distances add up to the same total
    • b) Both, because both travel along a straight track
    • c) Train X, because it covers equal distances in equal intervals of time
    • d) Neither, because no real train holds one speed for long

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

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

Answer key — Grade 7 Science — Speed and motion

  1. 1. 8
  2. 2. 100
  3. 3. c) The train, because 72 kilometers per hour is 20 meters per second
  4. 4. 75
  5. 5. 4
  6. 6. c) Train X, because it covers equal distances in equal intervals of time
  7. 7. 8
  8. 8. 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