# Homework Help: Displacement Question

1. Oct 21, 2007

### shell4987

A big olive (m = 0.15 kg) lies at the origin of an xy coordinate system, and a big Brazil nut (M = 0.46 kg) lies at the point (0.72, 2.8) m. At t = 0, a force o = (1 + 1) N begins to act on the olive, and a force n = (-2 -4) N begins to act on the nut. What is the (a)x and (b)y displacement of the center of mass of the olive-nut system at t = 3.1 s, with respect to its position at t = 0?

3. The attempt at a solution

Im not too sure about going about solving this problem can anyone give me a head start?

2. Oct 21, 2007

Break the problem into three parts:
1) Initial conditions
Find the center of mass of the olive-nut system.
Because this is a 2-d problem, apply the center of mass equation for each direction: x direction, and y direction.

2) Movement
Find out where the olive and nut moved to given the force on each and the time.

3) Final position
Find the final center of mass after they've moved.

Let me know if you need more details after you try it.

3. Oct 21, 2007

### shell4987

Okay, I found the xcom to be 0.108 and the ycom to be 1.288, but I don't know how to do part 2 because what equation do I use that involves force and time?