A body of mass M collides against a wall with velocity V and rebounds with the same speed. It's change of momentum is

Question

anonymous · Answer

No Change as such

anonymous · Answer

momentum= mass*velocity
both remain same after collision
so no change in momentum.

anonymous · Answer

Answer is given as 2MV

anonymous · Answer

But how? Are we to add both the momenta?

anonymous · Answer

adarsh  see the direction change as well
first it is +v next it is -v

anonymous · Answer

Okay. yeah, got it.
First, Its MV. Second is -MV. Subtracting, we get 2MV.

anonymous · Answer

By subtracting how we get 2MV

anonymous · Answer

But I don't understand why the sign is +ive in first case and -ive in second case.

anonymous · Answer

See, MV - ( - MV) = MV + MV = 2MV(Simple integer addition)

anonymous · Answer

Can anyone say about the signs?

anonymous · Answer

|dw:1329838538143:dw|because we shud maintain a standard sign system like think this way