Static & Kinetic Friction - Part III
You are pushing on a block that is resting on the table.
(a) You press on the block but not hard enough to start it
moving. What are the forces acting on the block? (Be sure to specify the type
of force and the object causing each force.) Wherever you can, compare the
magnitudes of forces. Give a brief explanation for how you know each of the
results you state.
(b) You press a bit harder and the block begins to move. After a moment of
starting up, you press so that the block is moving with a constant velocity.
For the time while the block is moving with a constant velocity have any of
the comparisons you stated in (a) changed? Which ones? Have any of the forces
changed? Which ones?
(c) Suppose the block has a mass of 0.4 kg and the coefficient of friction
between the block and the table is 0.3. What force will you have to use to
keep it going at a constant velocity of 0.2 m/s? (You may take g = 10 N/kg.)