The same force is applied to roll a boulder and a small baseball down a hill. The baseball stops at a small group of shrubs, while the boulder...

In the given example, the boulder, which is more massive, needs collision with a large tree to stop. In comparison, the basketball, which is lighter, requires a small group of shrubs. This clearly shows that more massive objects require more force to stop. This is because of inertia. More massive objects (such as boulders) have more inertia as compared to lighter objects (such as a small basketball). And it is the inertia of a body that resists any change in its state of motion. One can think about by using simpler examples. It takes more force to move a cricket ball than a tennis ball (from a state of rest), since the cricket ball is heavier than the tennis ball (and that is why cricket bats are heavier as compared to tennis rackets).

Hope this helps.