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

Answer:

6 s

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

$t=\frac{v}{g}=\frac{-58.8}{-9.8}=6 s$

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.