# Homework Help: Inertia question

1. Mar 20, 2014

### endaman95

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

Which of the following is an inertial frame of reference when the measuring sensitivity in not very high?
1. A frame of reference fixed to the Sun and its axes are pointing toward 3 other stars.
2.A frame of reference fixed to a laboratory table.

2. Relevant equations

3. The attempt at a solution
Im not sure about the sun. Any ideas?

2. Mar 20, 2014

### paisiello2

Here is my understanding of what is meant by an inertial reference frame:

An inertial reference frame is one that is not accelerating, meaning it is not changing speed or direction.

All frames of reference are, at best, approximations to an inertial reference frame. The sun and the stars in the universe are not fixed and are all moving and accelerating. However, for practical purposes we can assume the earth and the sun are good enough approximations to an inertial reference frame that we can usually ignore the small inertial forces associated with their movement.

3. Mar 20, 2014

### endaman95

I was thinking the same thing. Thank you for the answer.

4. Mar 20, 2014

### Staff: Mentor

Please remember not to do the student's homework for them. It is okay to provide hints, ask questions, suggest search terms, etc. But the student must do the bulk of the work on their schoolwork questions.