posted by Andrea .
a rock is thrown straight up which of the following statemetns concerning the net force acting on the rock at the top of the path is true? assume air resistance is negligible.
a)it's equal to the weight of the rock
b) it is instantanwously equal to zero
c) it's direction changes from up to down
d) it's less than the weigh of the rock
F=ma and at the top of the path the rock's velocity instantaneously zero. so wouldn't the answer be c?
Gravity is the net force acting on the rock to slow it down going up, and speed it up when going down. Doesn't gravity force equal weight, and it has a constant direction?