A 2.8 kg object is dropped, from rest, from a height of 15.5 m above the ground. Assuming air-resistance can be neglected, What is the kinetic energy of the object just before it hits the ground?

A 7.80-g bullet moving at 570 m/s penetrates a tree trunk to a depth of 4.40 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.

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 50.2-g golf ball is driven from the tee with an initial speed of 58.0 m/s and rises to a height of 22.4 m. (a) Neglect air resistance and determine the kinetic energy of the ball at its highest point. (b) What is its speed when it is 7.23 m below its highest point? (a) Number (b) Number Units Units

In the figure, a block of mass m = 1.30 kg slides head on into a spring of spring constant k = 390 N/m. When the block stops, it has compressed the spring by 6.60 cm. The coefficient of kinetic friction between block and floor is 0.330. While the block is in contact with the spring and being brought to rest, what are (a) the work done by the spring force and (b) the increase in thermal energy of the block-floor system? (c) What is the block's speed just as the block reaches the spring?

A 1.4 kg textbook is thrown out of a window at 8.67 m/s and directed at an angle of 50.1° above horizontal. The window is 6.26 m above the ground. The textbook strikes the ground at a speed of 10.2 m/s. How much work is done on the textbook by air-resistance?

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?

A 7.80-g bullet moving at 560 m/s penetrates a tree trunk to a depth of 4.80 cm. (a) Use work and energy considerations to find the average frictional force that stops the bullet. (b) Assuming the frictional force is constant, determine how much time elapses between the moment the bullet enters the tree and the moment it stops moving.

You throw a tennis ball (mass 0.0570 kg) vertically upward. It leaves your hand moving at 15.0 m/s. Air resistance cannot be neglected, and the ball reaches a maximum height of 8.00 m. (a) By how much does the total mechanical energy decrease from when the ball leaves your hand to when it reaches its maximum height? (b) What is the magnitude of the average force of air resistance?

A 12.0 kg box is given an initial push that starts it sliding across the floor. It eventually comes to a stop. If the box has an initial velocity of 3.5 m/s, how much work is done by friction to cause it to come to a stop? (Yes, you are correct, you do not know the coefficient of friction.)