What is the average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge?

Question

asked Dec 3, 2019 180k views

1 Answer

Ladi · Answer 1 · 2019-12-09T02:58:04+0000

Answer:

Average speed, over the first 4.0 s of its motion, of a pebble released from rest off a bridge = 19.6 m/s

Explanation:

We have equation of motion ,
s= ut+(1)/(2) at^2 , s is the displacement, u is the initial velocity, a is the acceleration and t is the time.

In this case the initial velocity of body = 0 m/s, acceleration = 9.8
m/s^2 , we need to calculate displacement when t = 4 seconds.

Substituting

$S=0*t+(1)/(2) *9.8*4^2\\ \\ S=78.4 meter$

So a distance of 78.4 meter has been traveled by pebble in 4 seconds.

Average speed = 78.4/4 = 19.6 m/s