Potential Energy EX 4

From pwiki
Revision as of 17:58, 13 August 2011 by imported>Patrick
(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)
Jump to navigation Jump to search

The block slides down the distance 3 m and then continues to slide down some more. Let's assume that it slides some further distance . It means that the total distance the block moves down the incline is . It moves down the height . The spring which was initially uncompressed is now compressed by .

TOP

The question is to find the distance such that the total change in potential energy of the system (spring-block-Earth) is zero. To find this distance we will first compute the change of height from the triangle in the diagram above:



And then the change in gravitational potential energy using the equation:



And then compute the change in the spring's potential energy:



The total change in potential energy is then



Solving the quadratic equation for , we find m. Note that we select the positive solution since the distance is always positive.