How fast will it be traveling after it goes 21 m?

Question

An object accelerates from rest with a constant acceleration of 7.5 m/s2. 

Answer 1

I will put an answer in the Comments window due to problems editing in the Answer window.

Answer 2

distance = initial velocity * time + 1/2*acceleration*time^2

 

Starting from rest ---> initial velocity is zero;

 the first term in the formula cancels

 

21 = 1/2*7.5*t^2

 

Solving for t:

 

 42 = 7.5*t^2

 

t = square root ( 42/7.5)

 

   = 2.366 seconds

 

final velocity = initial velocity + acceleration * time

 

                   = 0 + 7.5 * 2.366

 

            17.745 meters per second