Question

A student wants to determine the effect of mass on kinetic energy. She will drop two balls of the same size into a pool of water.

Which investigation method should the student use?

(4 points)
Responses

She should drop two balls with different masses from the same height.
She should drop two balls with different masses from the same height.

She should drop two balls of the same mass from different heights.
She should drop two balls of the same mass from different heights.

She should drop two balls of the same mass from the same height.
She should drop two balls of the same mass from the same height.

She should drop two balls with different masses from different heights.

Answer 1

She should drop two balls with different masses from the same height.

Reason: to test the effect of mass you must keep height (and thus impact speed) the same. With the same size/shape (so similar air resistance) and same drop height, v is effectively the same, so kinetic energy 1/2 mv^2 changes only with m — isolating the mass effect.