A ball is dropped straight down from an unknown height with…

A ball is dropped straight down from an unknown height with an initial velocity of zero, and hit the ground 0.18 s later. Calculate the following variables:   A) Final velocity of the ball just prior to hitting the ground. B) Average velocity of the ball over the course of the drop. C) Height from which the ball was dropped. D) Average acceleration of the ball over the course of the drop.

Consider an individual who sits on a bench and performs a kn…

Consider an individual who sits on a bench and performs a knee-extension exercise (see figure below). The person is rehabilitating a knee injury and has a mass that can be attached to the shank (lower leg) to vary the difficulty of the exercise.  A) Which would require a stronger quadriceps (knee extensor muscle) contraction: performing the exercise with the mass attached at the ankle (as shown) or in the middle of the shank? Why? B) To lift the mass, would a positive or negative quadriceps (i.e., knee extensor muscle) torque need to be generated?