Question

Use the table of criteria for an investigation to answer the question.

Effect of Object Mass and Drop Height on Gravitational Study
Object To Be Dropped Drop Height (meters)
10-gram ball 5
5-gram ball 8
18-gram ball 10
A student designs an investigation to study the effect of gravity on objects on Earth. He will use the criteria shown. How can the student improve the investigation?

(1 point)

by measuring the circumference of the balls

by using balls that are the same mass

by dropping the balls from the same height

by finding balls made from different materials

Answer 1

by dropping the balls from the same height

Reason: the current design changes mass and height at the same time, which confounds the variables. To test how mass affects falling (or to test gravity), keep height constant so only mass varies (or vice versa — keep mass constant to test height).