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Year 7 Science — Measuring time

Say how old clocks kept time, find a pendulum's time period from a count of oscillations, and convert between the second, the minute and the hour.

Name: ________________________

Before you start

The parts of a simple pendulum, and where the bob reaches at one extreme.

1234
  1. 1. The support
  2. 2. The thread
  3. 3. The bob
  4. 4. One extreme

The dark bob hangs at the mean position, straight below the support. The pale one shows where it reaches at one extreme; there is a matching extreme on the other side. One oscillation is mean, extreme, across to the other extreme, back to mean.

  1. 1.What does a quartz clock count to keep time?

    • a) The turning of gears driven by a hanging weight
    • b) Very rapid vibrations of a quartz crystal
    • c) Drops of water falling through a fine hole
    • d) The swings of a very short pendulum

  2. 2.A song lasts 4 minutes. How many seconds is that? Answer with a number.

  3. 3.What did Galileo find when he timed a swinging lamp against his own pulse?

    • a) The time for a swing depended on how heavy the lamp was
    • b) The swings got faster as the lamp slowed down
    • c) Each swing took a little longer than the one before
    • d) Each swing took the same time as the one before

  4. 4.The time a pendulum takes to complete one oscillation has a two-word name. What is it?

  5. 5.Match each old timekeeping device to the steadily repeating thing it counted.

    • Sundial
    • Water clock
    • Hourglass
    • Candle clock
    • sand running from one bulb to the other
    • the moving shadow an object casts in sunlight
    • water flowing out of, or into, a vessel
    • a marked candle burning down

  6. 6.Two pendulums hang side by side. They are the same length, but one has a much heavier bob. What can you say about their time periods?

    • a) The heavier bob gives the shorter time period, because it swings with more force
    • b) There is no way to say without timing them
    • c) The heavier bob gives the longer time period, because it is harder to move
    • d) They are the same, because the time period depends on length rather than on the mass of the bob

  7. 7.A second pendulum takes 25 seconds to complete 10 oscillations. What is its time period, in seconds? Answer with a number.

  8. 8.Put the stages of one oscillation of a pendulum in order, starting from the moment the bob leaves the mean position.

    • It arrives back at the mean position
    • It swings across to the other extreme position and turns
    • The bob leaves the mean position
    • It reaches one extreme position and turns

Answer key — Year 7 Science — Measuring time

  1. 1. b) Very rapid vibrations of a quartz crystal
  2. 2. 240
  3. 3. d) Each swing took the same time as the one before
  4. 4.
    • time period
    • the time period
  5. 5. Sundial → the moving shadow an object casts in sunlight; Water clock → water flowing out of, or into, a vessel; Hourglass → sand running from one bulb to the other; Candle clock → a marked candle burning down
  6. 6. d) They are the same, because the time period depends on length rather than on the mass of the bob
  7. 7. 2.5
  8. 8. 1. The bob leaves the mean position 2. It reaches one extreme position and turns 3. It swings across to the other extreme position and turns 4. It arrives back at the mean position