The force constant of a spring is 800 N/m and the unstretched length is 0.76 m. A 1.9-kg block is suspended from the spring. An external force slowly pulls the block down, until the spring has been stretched to a length of 0.91 m. The external force is then removed, and the block rises. In this situation, the external force on the block before it is removed is closest to:

Which, if any, of the following statements concerning the work done by a conservative force is not true?

A 2 kg mass has 40 J of potential energy with respect to the ground. Approximately how high is it above the ground?

An 22-g steel ball is released from rest and falls vertically onto a steel plate. The ball strikes the plate and is in contact with it for 0.5 ms. The ball rebounds elastically, and returns to its original height. The time interval for a round trip is 6.00 s. In this situation, assume the plate does not deform during contact. The maximum elastic energy stored by the ball is closest to:

A body with mass m=4 kg is moving along straight line on a frictionless surface with speed v=10 m/s. At a certain point the surface becomes rough with a coeff. of friction μ=0.25. Find the distance from the beginning of the rough segment to a point at which the body’s speed is just a half of the initial speed in meters

Consider the system pictured (see document with pictures). A 4 kg block slides down the incline from a rest position located at a distance of 3 m (measured from the bottom of the incline). The surface of the incline is rough and has a friction coefficient of 0.1. Opposite to that the horizontal surface is frictionless.  What is the speed at the bottom of the incline?

Referring to the previous problem, the body will reach the spring (with a force constant k=1000 N/m) and depress it. What is the maximum compression (xmax) of the spring?

 A mass is pressed against (but is not attached to) an ideal horizontal spring on a frictionless horizontal surface. After being released from rest, the mass acquires a maximum speed v and a maximum kinetic energy k. If instead the mass initially compresses the spring twice as far:

A sand mover at a quarry lifts 2,000 kg of sand per minute a vertical distance of 12 meters. The sand is initially at rest and is discharged at the top of the sand mover with speed 5 m/s into a loading chute. At what minimum rate must power be supplied to this machine?

Compared to falling on a stone floor, a wine glass may not break when it falls on a carpeted floor because the

Mine is sknudsen, corresponding to MIX email sknudsen@mix.wvu.edu