# Harmonic motion and acceleration

1. Dec 17, 2013

### Lacnez

A system exhibits simple harmonic motion with a frequency of 0.85 cycles per second. Calculate the acceleration experienced by the mass 3.0 m from the equilibrium

This question seems simple, I haven't really tried anything cause I can't figure out how to start.

I need help to start this problem off

2. Dec 17, 2013

### ShayanJ

You should write the equation of motion,differentiate twice with respect to time and try to eliminate time between acceleration and position and then set position equal to 3 m!

3. Dec 17, 2013

### Lacnez

don't i lack the required information to use a motion equation

4. Dec 17, 2013

### haruspex

A quick test you can do is dimensional analysis. You are given a time and a distance, so in principle you might have enough information to calculate a velocity, or an acceleration, etc., but not, e.g. a force, since you are not given any quantities involving a mass dimension.
So, just go ahead and write out the equations. Maybe all the unknowns will disappear.

5. Dec 19, 2013

### PeterO

You could try to apply problem/puzzle logic.

Generally a question is asked when there is only one answer. Thus the answer you get if you assume the mass is 3 kg and maximum amplitude is 5.0 m will be the same as the answer when the mass is 1 kg and the maximum amplitude is 3.0 m

You could calculate both those answers, and if they are the same say "Wow; who would have thought!"

If the answers are different, you may then be able to do the "general" calculation to get the answer in terms of mass and maximum amplitude.