Question

Which has a greater momentum: a ship weighing 9.0⋅107 kg that is tied to a dock or a raindrop weighing 0.001 kg that is falling from a cloud? Use details to support your answer.

Answer 1

Momentum is defined as the product of mass and velocity of a body.

The ship has mass M = 9 x 107 kg. But it is tied to a dock. So it's velocity is zero. So, it's momentum is Pship = mass of ship x it's velocity = 9 x 107 x 0 = 0. That is the ship has huge mass, but as it's velocity is zero, it's momentum is also zero.

The mass of the raindrop is m = 0.001 kg. Let the velocity of rain drop at any instant is V, and as it is falling from cloud, V > 0. So the momentum of the raindrop is Praildrop = mass of raindrop x velocity of raindrop = 0.001 x V = 0.001V, which is not zero. Here the raindrop have a very small mass, but as it have some velocity, so it's momentum is greater than zero.

So as we can see, Praindrop > Pship . So the raindrop has greater momentum.