Question

A particle starts from rest with uniform acceleration and its velocity after n seconds is v.The displacemant of the body in last two seconds

Answer 1

The distance travelled by the particle in last 2 seconds=distance travelled by particle in nth second - distance travelled by particle in (n-2)th second so,

s=(1/2)an² - (1/2)a(n-2)²

 =(1/2)a.[n²-n²+4n-4]

 =a/2.[4n-4]

so,

velocity = acceleration*n(time)

a=v/n

s=2(v/n).(n-1)