Question

A body starts from rest and moves for n seconds with uniform acceleration a, it's velocity after n seconds is v. The displacement of the body in last 3 second is :

Answer 1

For finding displacement we have to calculate the initial velocity during those three seconds.

Therefore let U1 be the velocity before last 3 seconds
U1=u+a(n-3)sec
U1=0+a*(n-3)=a(n-3)

Now we know that
V²-U1²=2a*displacement
Displacement =[v²-a(n-3)]/2a metres