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Bml
Bml
11:14
@JohnRennie Hi :-)
Hi :-)
Bml
Bml
@JohnRennie I have a doubt on this exercise: "A point-like body A moving with velocity v on a smooth horizontal plane bumps into a body B, equal to the first, initially stationary, at the foot of a smooth inclined plane. Find the maximum height at which body B reaches the inclined plane in the two cases of elastic collision and completely inelastic collision."
OK, where are you running into problems with this?
Bml
Bml
@JohnRennie Because the solution I have seen uses conservation of momentum $mv = mv_A + mv_B$, but how can we do this since the velocity after collision has two components and we do not know the angle of inclination?
The question assumes motion in one dimension i.e. the bodies move along a straight line both before and after the collision.
Do you want to go through the calculation?
Bml
Bml
11:21
@JohnRennie Why? Body A is on a horizontal plane, while body B is on an inclined plane. Why does it only assume motion along the horizontal direction?
What happens is A collides with B and immediately after collision B has some (horizontal) velocity in the same direction as A's original velocity.
Now B starts to ascend the slope, and we find how high it gets using conservation of energy i.e. mgh = ¹⁄₂mv²
So it's a two stage process.
Does this help?
Bml
Bml
@JohnRennie Yes.
OK :-)

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