A group of students is investigating how a force applied to an object affects the motion of the object. The diagram shows the setup fo the investigation. To create a force, the students add a weight to the weight holder
and observe whether the cart moves. The students repeat this step five times, using a different amount of
weight each time.

"mass of the objects and the distance between two objects."

Explanation:

The force of gravity is a function directly proportionate to the product of the two masses of the two objects under consideration, and indirectly proportionate to their squared distance.

The relationship is made exact by inserting the gravitational constant G

with a value that was measured by Cavendish in a clever experiment, back in the days.