# Theoretical angular momentum problems

## Homework Statement

1. Folk wisdom says that a cat always lands on its feet. If a cat starts falling with its feet up, how can it land on its feet without violating the law of conservation of angular momentum ?

2. Is it easier to crawl radially outward or radially inward on a rotating merry-go-round ? Why ?

## Homework Equations

Conservation of angular momentum:

## The Attempt at a Solution

1. I think by spinning around its center of mass but I am not sure. What do you guys think ?

2. I guess this one has to deal with conservation of angular momentum but I don't know how to start it. Any hint ??

Nabeshin
Science Advisor

## Homework Statement

1. Folk wisdom says that a cat always lands on its feet. If a cat starts falling with its feet up, how can it land on its feet without violating the law of conservation of angular momentum ?

2. Is it easier to crawl radially outward or radially inward on a rotating merry-go-round ? Why ?

## Homework Equations

Conservation of angular momentum:

## The Attempt at a Solution

1. I think by spinning around its center of mass but I am not sure. What do you guys think ?

2. I guess this one has to deal with conservation of angular momentum but I don't know how to start it. Any hint ??

1. To spin would be to change the angular momentum, so how can the cat reorient itself so that $$\Delta L=0$$?

2. Consider that you know angular momentum must be conserved in all cases, but energy need not be. What happens to the total energy when someone moves radially closer or farther away?

2. Kinetic energy will increase when the radius is shorter. So it means it is easier to crawl outside ??

Nabeshin
Science Advisor
2. Kinetic energy will increase when the radius is shorter. So it means it is easier to crawl outside ??

Right-o, you have to do work to decrease your radius, and work is done on you to increase your radius. How about the first one? Any thoughts?

I cannot think of anything yet. Any hint ?