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## Momentum

From classical mechanics to quantum field theory, momentum is the Universe's preferred language to describe motion. Learn here about momentum, its conservation, and how it captures our intuitions.

# Warmup

If a car and a bus are moving with the same momentum, which has greater kinetic energy?

Assumptions and Details

• The car has a much smaller mass than the bus.

A person is falling freely under the gravity. He has a heavy briefcase in his hand. There is swimming pool just beside his vertical line of fall. If he wants to land in the swimming pool, what should he do?

Rain drops fall on the ground with a speed and a momentum. They hit different objects and create sound. Suppose, 100 drops are hitting a horizontal surface of unit area per second. The speed of rain drops 15 m/s in vertically downward direction. The mass of each drop is 0.05 grams. If the rain drops come to rest immediately after hitting the surface then, find the force experienced by the horizontal surface?

When the two objects collide, they apply large forces to each other. These forces are called as impulsive forces. Such forces act for a very small duration of time, but still produce large changes in the momentum of the colliding objects.

Let's consider a case of collision between a ball and a bat. The ball of mass $$m$$ is coming towards the batsman with a speed of $$v$$ m/s and the bat hits the ball to return it with the same speed, along the same line. What will be the impulse of the force of the bat, on the ball?

When a ball is dropped from a height, after hitting the ground, the ball rebounds. The rebounded height is less than the original height of the drop. What can be said about the collision between the ball and the ground?

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