A rock is kicked horizontally at a speed of 15 m/s from the edge of a cliff. The rock strikes the ground 65 m from the foot of the cliff of height H as suggested in the figure, which is not drawn to scale. Neglect air resistance.

-How long is the rock in the air?
A)1.0 s
B)1.2 s
C)4.0 s
D)5.5 s
E)11.2 s

Question

A rock is kicked horizontally at a speed of 15 m/s from the edge of a cliff. The rock strikes the ground 65 m from the foot of the cliff of height H as suggested in the figure, which is not drawn to scale. Neglect air resistance.

-How long is the rock in the air?

-How long is the rock in the air?
A)1.0 s 
B)1.2 s 
C)4.0 s 
D)5.5 s 
E)11.2 s

Quizplus · Accepted Answer

The time a rock is in the air depends on the initial velocity and the height from which it is thrown. Without additional information, the most reasonable choice for a typical problem involving a rock thrown or dropped is 4.0 seconds, assuming a moderate height and initial velocity.

A Rock Is Kicked Horizontally at a Speed of 15