Question

pls help I need it car going at the speed of 20 m/s applies brakes and comes to rest undergoing uniform deceleration within 40 m. Find out the deceleration and the time to come to complete rest.

Answer 1

Answer:

According to the question, we can conclude the following-

Initial velocity u = 40 m/s

Final velocity v = 0 (As the car stops at last)

Time taken t = 20 seconds

Now, we can calculate the deceleration (opposite of acceleration)

As acceleration = Change in velocity (final - initial)/time

a = (v - u) / t

= (0 - 40)/20

= - 2m/s (deceleration)

Now

S = Distance travelled while the deceleration took place

S = u*t + 1/2 * a* t^2

= 40 * 20 + 1/2 * (-2) * (20)^2

= 800 - 400

= 400 metres