3. Daniel stands on a bridge over a river. He drops a coin and notes that the coin takes 3 s to reach the river below. He must be standing

above the river.

A 10 m

B. 15 m

C. 30 m

D. 45 m

45 m

Explanation:

Initial velocity of the coin = 0 m/s  (since he dropped it from his hands)

time spent in falling - 3 sec

distance s = ?

using

s = ut + g

where

s is the distance the stone fell

u is the initial velocity

t is the time spent falling

g is acceleration due to gravity = 10 m/s^2 (positive downwards)

substituting values, we have

s = (0 x 3) +  (10 x )

s = 45 m

0.11 m/s and 0.28 m/s should be correct