Time a fall and compare fairly

Distance needs a clock

Two falling objects can cover the same distance in different times. To describe average speed, divide the distance traveled by the time taken. Our practice record describes a paper object moving down sixty centimeters in four tenths of a second. The numbers are invented for learning.

Keep the units together

Sixty centimeters is zero point six meters. Divide zero point six by zero point four. The average speed is one point five meters per second. That number describes the whole measured trip. It is not automatically the speed at the final moment.

A stopwatch is not magic

A short fall happens quickly. Starting or stopping a timer a little late can change the result noticeably. Scientists repeat measurements and think about how they measured. A stopwatch can show many digits without knowing exactly when your finger decided to press its button.

Read three trials

Our three invented times are zero point four two, zero point three eight, and zero point four zero seconds. They used the same object, release height, and method. Add the three times and divide by three. The mean time is zero point four zero seconds.

Pause and compare

Imagine another object takes zero point six seconds to cover the same zero point six meters. Pause and compare its average speed with the first object. Does taking longer make the average speed larger or smaller? Use both the distance and the time in your explanation.

Check the average

The second average is one meter per second, so it is smaller. The first object covered the same distance in less time. Keep the comparison fair: do not quietly change the distance halfway through your explanation. That would give the numbers a secret shortcut.

Count time in a video

Here is a useful fact: video frames can act like clock marks. Twenty four frame intervals at sixty frames per second span four tenths of a second. Count intervals, not just pictures. You also need reliable timing, a distance scale, and a clear view.

Use careful evidence

Continue to the worksheet to calculate averages and read repeated trials. Use our practice data first. Any real observation must be adult guided, using only light paper close to a clear floor. Never use people, pets, heavy objects, stairs, windows, or high places as drop experiments.