# DQ1C_solution - Discussion Question 1C P212 Week 1 Review...

This preview shows pages 1–2. Sign up to view the full content.

Discussion Question 1C P212, Week 1 Review: Potential Energy 1 Four particles of equal mass M are fixed at the corners of a square with sides of length a . A fifth particle has mass m and moves under the gravitational forces of the other four. Consider the gravitational potential energy U of the mass m as a function of its position ( x , y ). This potential energy map U ( x , y ) is an extremely useful way of representing the effect of the gravitational force on the mass m : If m is held at rest at some point ( x 1 , y 1 ) and you let it go, it will always move toward a point of lower potential energy. You can therefore think of the function U ( x , y ) as a topographical map: the particle m will always “roll downhill” . If the mass m moves from point ( x 1 , y 1 ) to point ( x 2 , y 2 ), the potential energy difference U ( x 1 , y 1 ) – U ( x 2 , y 2 ) tells you exactly how much work was done by gravity, and exactly how much kinetic energy the particle gained as a result. Let’s visualize all this. The figures below show the potential energy map U ( x , y ) for the square configuration of four masses M illustrated above. The height of the surfaces indicates the magnitude of U at each point. Which one is correct?

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

## This note was uploaded on 06/16/2011 for the course PHYS 212 taught by Professor Kim during the Spring '08 term at University of Illinois, Urbana Champaign.

### Page1 / 3

DQ1C_solution - Discussion Question 1C P212 Week 1 Review...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document
Ask a homework question - tutors are online