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Unformatted text preview: Physics 8A John Rville Sections 112 & 201 email@example.com Physics 8A Work and Energy Laboratory a) This is a graph of the net force versus time. If it were only the weight then the graph would show only a constant line with a value close to g m .- Newtons. If it were only the applied force, there would be a part of the graph were the force would be zero (when the ball is in the air). b) Free body diagrams : Your free body diagrams should look like the following. Most of you were confused by the FBD when the ball is caught. However, if you think of what happens physically, the ball is being slowed down when it is caught (or youre in trouble) therefore it needs an upwards acceleration and so applied F r must be greater in magnitude than W r . Physics 8A John Rville Sections 112 & 201 firstname.lastname@example.org i) The FBD than would be different in the case of projectile motion would be the those where applied F r appears. Because in projectile motion you have a horizontal movement in addition to the vertical movement, there needs to be a slanted force during the tossing (and it will also be the case when it is caught). j) The only time you can have applied F r that is equal to W r in magnitude is when the ball is at rest (before the tossing, and after the catching) so that you have the equilibrium condition r r = net F . k) The applied force is greater than the weight force when the ball has an upward acceleration....
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