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The first question on the exam was the following:
A rock is thrown straight up from the Earth's surface. Which one of the following statements
concerning the net force acting on the rock at the top of its path is true?
(a) The net force is instantaneously equal to zero newtons.
(b) The net force is greater than the weight of the rock.
(c) The net force is less than the weight of the rock, but greater than zero newtons.
(d) The direction of the net force changes from up to down.
(e) The net force is equal to the weight of the rock.
"The force pushing the rock up equals the force of gravity pulling it down so at the top its
acceleration is zero and the net force is zero."