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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.

# Momentum of an Object

A $$69\text{ kg}$$ stuntman jumps out of a window and lands on a trampoline $$5\text{ m}$$ below. What is the magnitude of his momentum at the point he hits the trampoline?

Assumptions

• The air resistance is negligible
• The gravitational acceleration is $$g=10\text{ m/s}^2.$$

An object of mass $$4\text{ kg}$$ is thrown straight upward into the air at a velocity of $$15\text{ m/s}$$ from the edge of a cliff. Let $$p_1$$ be the momentum of the object $$1$$ second after the throw, and $$p_{4}$$ the momentum of the object $$4$$ seconds after the throw. Then what is $$\displaystyle{\frac{p_{4}}{p_1}}?$$

Assume that gravitational acceleration is $$g=10\text{ m/s}^2.$$

Two objects $$A$$ and $$B$$ are moving on the ground in the same direction at $$5\text{ m/s}$$ and $$2\text{ m/s},$$ respectively. Their respective masses are $$3\text{ kg}$$ and $$4\text{ kg}.$$ Now, they both start to accelerate uniformly at $$-3\text{ m/s}^2$$ and $$0.5\text{ m/s}^2,$$ respectively, at the same time. Four seconds after that, what is the sum of their linear momenta?

A $$1\text{ kg}$$ ball is rolling on the floor at $$4\text{ m/s}.$$ Find the momentum of the ball.

An object initially at rest falls freely in an atmosphere free of air resistance. After $$t$$ seconds, the kinetic energy of the object is $$x\text{ J}$$ and the momentum of the object is $$y\text{ kg}\cdot{m/s}.$$ If $$x=y,$$ what is the value of $$t?$$

Assume that gravitational acceleration is $$g=10\text{ m/s}^2.$$

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