Question

8.
A particle moving with an initial
velocity of 5 m/s is subjected to a
uniform acceleration of - 2.5 ms
The displacement in the next 4
seconds is :
​

Answer 1

5*2.5/4 will be your answere

Answer 2

First of all, since we want to find displacement. Find the time i whcih the particle stops.

u = 5 m/s 

v = 0

a = - 2.5 m/s^2

t = ??

v = u + at

0 = 5 - 2.5t

2.5t = 5 

t = 2 s

So, the particle stops after 2 s.

Distance travelled within these two seconds -

s = 5*2 + 1/2*(-2.5)*(2^2)

s = 10 - 5 = 5 m

Now, since the object is travelling for more 2 sec and we have 

u = 0

v = ??

t = 2 

a = 2.5 (in opposite direction)

s = ut + 1/2at^2

s = 0 + 5

s = 5 m in opposite direction.

So, displacement = 5 - 5 = 0