# Homework Help: Free Body Diagrams & 3rd law pair forces.

1. Oct 5, 2008

### JasonS

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

I have 2 questions from a practice test paper that I can't do (I missed the lessons) - I've attached them, the other questions I did fine. They should be quite basic but I'm not sure if what I'm doing is right (only done physics for 2 weeks). If anyone could correct my current solutions, and/or help on the others that would be great.

2. The attempt at a solution

In Q1 (a) I put on weight/reaction force on the magnet... and I know that there would be another force acting on it (from the other magnet) but I don't know where to draw it, or what it would be called.

In Q1 (b) I put the reaction to weight, upwards in direction acting on the earth.

In Q2 (a) I drew tension/weight on the pendulum and just weight on the earth.

Q2 (b) I'm not really sure about.

If anyone could help that would be greatly appreciated. Sorry for my English, it isn't my first language. Thanks in advance.

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2. Oct 5, 2008

### Staff: Mentor

Three forces act on the magnet. What are they and in what direction do they act? What's the third law pair for each force?

On the pendulum, two forces act. For the orbiting earth, how many forces act?