Question

An object, which is initially at rest, accelerates at a rate of 10 m/s2 . Its final position is 85 m from its initial position at the end of that acceleration. For how much time did it accelerate?

Answer 1

4.12 seconds

Step-by-step explanation:

From the kinetic equation

`s=ut+0.5at^(2)` where s is the displacement, u is initial velocity, t is time of travel and a is acceleration.

Since the object is initially at rest, the initial velocity is zero hence the equation can be re-written as

`s=0.5at^(2)` and making t the subject of the formula

`t=\sqrt {\frac {2s}{a}}`

Substituting s for 85 m and a for 10 m/s2

`t=\sqrt {\frac {2*85 m}{10}}=4.123105626 s`

Therefore, time is approximately 4.12 seconds