Phil leans over the edge of a cliff and throws a rock upward at 5 m/s. Neglecting air resistance, one second later the rock's speed is
A)zero.
B)5 m/s.
C)10 m/s.
D)15 m/s.
E)none of the above

Question

Quizplus · Accepted Answer

Neglecting air resistance means that there is no external force acting on the rock other than gravity. Therefore, the rock will continue to move upward with a decreasing velocity due to the constant acceleration due to gravity (g = 9.8 m/s^2). At t=1s, the rock will have a velocity of 5 m/s upward.

Phil Leans Over the Edge of a Cliff and Throws