Question

A particle starts from rest with uniform acceleration a. Its velocity after n seconds is V. The displacement of the body in the last 2 seconds is ​

Answer 1

Answer:

a particle starts from rest so, initial velocity of a particle, u = 0 particle acceleration with uniform acceleration a

so, particle must follow all kinematical equations.

I mean , S = it+1/2at²

At u = 0, S = 1/2at²

here S is displacement during time .

therefore displacement in last 2 sec- distance travelled bin (n-2) sec

= Sn - Sn-1

= 1/2 an² - 1/2a(n - 2)²

= 1/2 a ( n² - n² + 4n - 4 )

= a (2n - 2 )

So , displacement in last 2 sec = a(2n-2)

A/C to question, Final velocity = v

Time = t

Acceleration = a

then, use formula,

v= u+ at

initial rest so, u = 0

v = a*n

a= v/n

Now, displacement in last 2 seconds= v/n(2n - 2) = 2v/n