Six problems due Monday, and I have no idea what I'm doing on either of these.(adsbygoogle = window.adsbygoogle || []).push({});

Problem 1:

1. The problem statement, all variables and given/known data

A group of people has a total mass of 1500kg and are standing on one end of a 20,000kg boat. They walk 6.5m to the other end of the boat. How much does the boat move? The water is frictionless.

2. Relevant equations

r_{com}= (1/M)*[itex]\int[/itex](r)dm

3. The attempt at a solution

I really have no idea where to begin, let alone how to try to solve it.

Problem 2:

1. The problem statement, all variables and given/known data

A regular pentagon has sides of lengtha. Find the center of mass if you remove the triangle formed by the geometric center and the two vertices on the bottom of the pentagon.

2. Relevant equations

r_{com}= (1/M)[itex]\int[/itex](r)dm

3. The attempt at a solution

The book says to split the rest of the pentagon into four equal triangles, and I found the center of mass of the removed triangle. Since the five triangles that make up the pentagon are the same, their centers of mass should be the same distance from the geometric center of the pentagon, which I'm using as the origin.

Also, the book says the answer to this one is ".115a above the vertex of the removed triangle."

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# Center of Mass: Boat and regular pentagon

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