Physics Question

Question

a student throws a rock horizontally from the edge of a cliff that is 20 m high. The rock has an initial speed of 10 m/s. If air resistance is negligible, the distance from the edge of the base of the cliff to where the rock hits the level ground below the cliff is most nearly

a. 20 m

b. 5 m

c. 10 m

d. 40 m

Answer 1

Calculate the time of flight t, which is the time it hits the ground, and then multiply the horizontal speed by the time of flight to get horizontal distance x.

h = gt² / 2 ⇒

t = √(2h/g)

Plug in

h = 20 m

g = 9.8 m/s²

and get t in seconds. Then

x = vt

Plug in the value you get for t, plug in

v = 10 m/s

and get x in meters.