Momentum and CollisionHard
Question
A ball moving with a velocity v this a massive wall moving towards the ball with a velocity u. An elastic impact lasts for a time ᐃt.
Options
A.The average elastic force acting on the ball is 
B.The average elastic force acting on the ball is 
C.The kinetic energy of the ball increases by 2m(u + v)
D.The kinetic energy of the ball increases the same after the collision
Solution
pi = - mv , pf = m(v + 2u) ∴ ᐃp = 2m (v + u)
∴ Force =
KEintial =
mu2 , KEfinal = 
m (2v + u)2
∴ ᐃKE =
[4v2 + u2 + 4uv - u2]
=
m[4v(v + u)] = 2mv (u + v)
∴ Force =
KEintial =
mu2 , KEfinal = m (2v + u)2∴ ᐃKE =
[4v2 + u2 + 4uv - u2]=
m[4v(v + u)] = 2mv (u + v)Create a free account to view solution
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