time and motion

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Across
  1. 2. distance moved in unit time.
  2. 4. the time taken by a pendulum.
  3. 5. comparison of some unknown quantity with some fixed quantity.
  4. 6. a substance whose
  5. 7. it is not constant.
Down
  1. 1. that can be measured.
  2. 2. a weight hung from a string.
  3. 3. travels in a straight line.