Falling speed: follow the clues

One ball, several pictures

Here is one soft ball shown at several moments. These are not four different balls waiting in a line. We are looking at pictures of the same fall. Each new picture shows the ball a little later, as it moves toward the floor.

A fair picture clock

Our picture clock waits the same short time before taking each picture. That matters. If the clock waited longer for one picture, a bigger gap might just mean more time passed. Equal time steps help us compare how the ball moves.

Look at the growing gaps

At first, the next picture is close by. Later, the gap is larger. The ball covers more distance during the same amount of time. That is a clue that it is getting faster. The pictures are a simple model of a fall with no air resistance.

Gravity changes the motion

Gravity pulls the ball toward Earth. In this model, that pull makes the falling ball speed up. Gravity has not gotten stronger just because the ball is moving faster. The pull keeps changing the motion while the ball is still above the floor.

Pause and choose

Pause and look at the spaces between the pictures. Are the later gaps bigger or smaller? If the picture clock waits the same time, does a bigger gap mean faster motion or slower motion? Explain your idea before you press play again.

Read the clue

The later gaps are bigger, so the ball moves faster in this picture model. Here is a fun fact: a set of still pictures can help us study motion. The ball does not need to wear a tiny speedometer. The picture timing gives us a useful clue.

Air can change the story

Real objects fall through air. A flat piece of paper may flutter and turn instead of following this neat picture pattern. Air can push against a falling object. Do not use one ball picture to claim that every object falls in exactly the same way.

Your next step

Continue to the worksheet and read the picture clues. You can point and explain before choosing an answer. Use the drawings for this activity. Never climb, jump, or drop things from a window to test a fall. A useful science question does not need a risky experiment.