A 3.13 kg object is dropped, from rest, from a height of 11.7 m above the ground. Assuming air-resistance does -14.3 J of work on the object as it falls to the ground. What is the kinetic energy of the object just before it hits the ground?

A bicyclist starting from rest applies a force of F = 239 N to ride his bicycle across flat ground for a distance of d = 210 m before encountering a hill making an angle of θ = 17 degrees with respect to the horizontal. The bicycle and rider have a mass of m = 120 kg combined. In this problem, you can ignore air resistance and other losses due to friction.How much work, W in joules, did the rider do before reaching the hill? What is the bicycle's speed, v in m/s, just before the hill? If the cyclist starts coasting at the bottom of the hill, what distance, di in meters, does the bike travel up the incline?

A 76.0-kg hiker is descending a mountain that has a peak altitude of 2350 m above sea level. The hiker has a device that measures her potential energy, and when she is at the peak of the mountain she decides to "zero" it (that is, she set's the zero point of potential energy to be the mountaintop). What does her potential energy device read sometime later on her descent when she is 1960 m above sea level?

An object of mass 2.0 kg has a velocity of (î 7 + j2 ) m/s. A force acts upon it and does 22 Nm of work on it. What is its final speed?

A ball with a mass of 500 g is thrown directly upward by a boy standing over a 5 m hole in the ground. The ball leaves the boys hand at a height of 1 m above the ground and with a speed of 10 m/s. What is the total mechanical energy of the ball when it hits the bottom of the hole? Take ground level to be the zero of gravitational potential energy. Assume air resistance is negligible.

A 2.03 kg mass is initially at rest upon a horizontal surface. An applied force of 17.6 N i then acts on the object over a distance of 2.92 m. If the final velocity of the object is 4.09 m/s i, what is the work done by kinetic friction over that distance moved?

A 65g Frisbee is thrown from a point 1.20 m above the ground with a speed of 12.00 m/s. When it has reached a height of 2.70 m, its speed is 10.4831 m/s. How much work was done on the Frisbee by its weight?

4

The surfer in the photo is catching a wave. Suppose she starts at the top of the wave with a speed of 2.98 m/s and moves down the wave until her speed reaches 9.56 m/s. The drop in her vertical height is 2.76 m. If her mass is 59.6 kg, how much work is done by the (non-conservative) force of the wave?

4. A 6.00-kg watermelon is dropped from rest from the roof of a 30.0-m-tall building and feels no appreciable air resistance. (a) Calculate the work done by gravity on the watermelon during its displacement from the roof to the ground. (b) Just before it strikes the ground, what is the watermelon's (i) kinetic energy and (ii) speed? (c) Which of the answers in parts (a) and (b) would be different if there were appreciable air resistance?