A particle accelerates uniformly from rest at 6.0m/s for 8s and then decelerates uniformly to rest in the next 5s. Determine the magnitude of the deceleration

John Perolski
August 07, 2023

Physics Past Questions & Answers on SPEED, VELOCITY AND ACCELERATION 



 Question 3

A particle accelerates uniformly from rest at 6.0m/s for 8s and then decelerates uniformly to rest in the next 5s. Determine the magnitude of the deceleration. WAEC 2005

Solution

You are to calculate the particle’s deceleration. It decelerated to rest from a particular velocity which was attained during acceleration. So, you are to calculate the velocity attained as follows:

Initial velocity, u = 0; acceleration, a = 6m/s ; t = 8s; 

velocity attained, v = ? 

Substituting into the most appropriate equation, v = u + at 

v = 0 + 6x8

. v = 48/wIs x

Next the particle decelerated to rest from a velocity of 48m/s, therefore, the deceleration 

is calculated thus:

Initial velocity, u = 48m/s; final velocity, v = 0; time, t = 5s; 

deceleration, a = ? 

Substituting into the most appropriate equation, 

v = u + at 

0 = 4 8 + a x 5

0 = 48 + 5o 

- 5a - 48

-5a/5 =48/5 

a= 9.6m/s^2