Question

A particle is moving on an axis Ox. From time t=0 to time t=32 the particle is travelling at a constant speed 15ms-1. The particle then decelerates from 15ms-1 to rest in T seconds

Find the value of T @Engineering

Answer 1

I don't think you have given enough information to solve this problem. e.g. if it decelerated at a very slow rate of deceleration, then it would take it a lot longer to come to rest than if it decelerated at a very high rate of deceleration.

Answer 2

Assuming acceleration is constant...

u = 15m/s, v = 0m/s, t = T.

v = u + at
0 = 15 + at
at = -15
t = -15/a = T

As asnaseer said, you need some more information to get any more than an expression.