Question

A motorcyclist changes the velocity of his bike from 20.0 meters/second to 35.0 meters/second under a constant acceleration of 4.00 meters/second2. How long does it take the bike to reach the final velocity?

Answer 1

we know that acceleration is the rate of change in velocity, hence a= (v-u)/t (note that v= final velocity and u=intial velocity).
Hence, making t the subject of the eqn, we will have t= (v-u)/a .
Sub in the values given in the question into the eqn: v= 35m/s , u= 20m/s and a = 4m/s^2 and solve for t.

Answer 2

Initial Velocity of the motorcyclist=20.0m/s (u)
Final Velocity of the motorcyclist=35.0m/s (v)
acceleration=4.00m/s^2

According to the first law of motion-
v=u +at
now making t the subject of the formula-
v=u +at
(v -u)= at
(v-u)/a=t
Now substituting the values in the formula-
(35 -20)/4 =t
15/4=t
3.75s =t

Ans- The Bike took 3.5s to reach the final velocity.