7. A force can speed up or slow down an object. A force can change the direction in which an object is moving. A bigger force on an object will produce a bigger change in the motion. A heavier object requires a larger force than a lighter object in order to undergo the same change in motion.

8. Forces affect how objects move. They may cause motion; they may also slow, stop, or change the direction of motion of an object that is already moving. Since force cause changes in the speed or direction of an object, we can say that forces cause changes in velocity.

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