Question

Find the initial velocity of a car which is stopped in 10 second by applying brakes. Retardation due to brake is 2.5 m/s2.

Answer 1

time taken = 10s
final velocity = 0
acceleration = -2.5m/s^2

using first equation of motion

v = u + at
0 = u + (-2.5)(10)
0 = u + (-25)
25 = u


so, the inital velocity of the body was 25m/s

Answer 2

Time = 10 sec, Retardation = -2.5 m/s^2 and Final velocity = 0 m/s

v = u + at (First Equation Of Motion)

=> 0 = u + (-2.5)(10)

=> 0 = u - 25.0

=> -u = -25.0

=> u = 25 m/s