This preview shows page 1. Sign up to view the full content.
Unformatted text preview: acceleration equation implies that so Alternative approach: The total work done by friction going up and down the board is
(the same work up and down) and gravity is a conservative force
(zero work on the round trip), so by the WorkEnergy theorem, Thus, . Solving for the final speed gives 2. [13pt] If a box of mass
5.50 kg is set on a large spring, it
compresses the spring a distance
11.0 cm from its
equilibrium position.
(a) [7pt] Suppose the same box is now lifted to a height above
the top of the uncompressed spring and dropped on it,
compressing the spring a distance
44.0 cm (so that
From what height was the box dropped? The fact that the box sits at rest on the spring with compression
implies that the forces
balance there, so
if is the spring constant. If the box is dropped from height
above the uncompressed spring, and the gravitational energy is taken to be zero at the top of
the uncompressed spring, energy conservation implies Then (11.0 cm) cm. 3 Note: The mass was not needed in the problem, but giving it permits an alternative solution in
which
490 N/m is obtained first. Then, when the spring...
View
Full
Document
This document was uploaded on 03/09/2014 for the course PHYS 221 at Ohio Northern University.
 Fall '12
 ScottYost
 Physics, Force, Friction

Click to edit the document details