At the top of a pole vault, an athlete actually can do work pushing on the pole before releasing it. suppose the pushing force that the pole exerts back on the athlete is given by f(x) = (140 n/m )x - (190 n/m2 )x2 acting over a distance of 0.19 m .how much work is done on the athlete?

Which of the following are guidelines to follow for obtaining accurate observations

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?

Aball with a mass of 275 g is dropped from rest, hits the floor and rebounds upward. if the ball hits the floor with a speed of 2.40 m/s and rebounds with a speed of 1.70 m/s, determine the following. (a) magnitude of the change in the ball's momentum (let up be in the positive direction.)