Question

7. If the acceleration due to gravity is -9.8 m/s2

A. How long will it take a freely falling body to acquire a speed of 58.8 m/s?

Answer 1

6 s

Step-by-step explanation:

Since the motion of an object in free fall is a uniformly accelerated motion, we can use the following suvat equation:

v = u+at

where

v is the velocity after a time t

u is the initial velocity

`a=g=-9.8 m/s^2` is the acceleration of gravity

Assuming the body is dropped from rest (so, u = 0), therefore, the equation becomes

`v=gt`

So, the time t at which the velocity becomes -58.8 m/s is

`t=(v)/(g)=(-58.8)/(-9.8)=6 s`

So after 6 s, the velocity of the body is -58.8 m/s, where the negative sign indicates the downward direction. Since the speed is just the magnitude of the velocity, this means that the speed of the body after 6 s will be 58.8 s.