1- The brakes of a truck cause it to slow down by applying a retarding force of 2.50 103 N to the truck over a distance of 870 m. What is the magnitude of the work done by this force on the truck? J Is the work positive or negative? Why?

1- The brakes of a truck cause it to slow down by applying a retarding force of 2.50 103 N to the truck over a distance of 870 m. What is the magnitude of the work done by this force on the truck? J Is the work positive or negative? Why?
…………………………………………………………………………………………………………………………………….. 2- A cable lifts a 990 kg elevator at a constant velocity for a distance of 30 m. What is the work done by each of the following?
(a) the tension in the cable J (b) the elevator’s weight J
3- A person pulls a toboggan for a distance of 30.0 m along the snow with a rope directed 25.0° above the snow. The tension in the rope is 68.0 N.
(a) How much work is done on the toboggan by the tension force? J (b) How much work is done if the same tension is directed parallel to the snow? J
4- During a tug-of-war, team A pulls on team B by applying a force of 1250 N to the rope between them. How much work does team A do if it pulls team B toward them a distance of 1.6 m? J
5- A person pushes a 16.0 kg shopping cart at a constant velocity for a distance of 20.0 m. She pushes in a direction 30.0° below the horizontal. A 34.0 N frictional force opposes the motion of the cart.
(a) What is the magnitude of the force that the shopper exerts? N (b) Determine the work done by the pushing force. J (c) Determine the work done by the frictional force. J (d) Determine the work done by the gravitational force. J
6- A 0.064 kg arrow is fired horizontally. The bowstring exerts an average force of 50 N on the arrow over a distance of 0.75 m. With what speed does the arrow leave the bow? m/s
7- When a 0.045 kg golf ball takes off after being hit, its speed is 40 m/s.
(a) How much work is done on the ball by the club? J (b) Assume that the force of the golf club acts parallel to the motion of the ball and that the club is in contact with the ball for a distance of 0.006 m. Ignore the weight of the ball and determine the average force applied to the ball by the club. N 8- A 6.50 http://www.webassign.net/images/multiply.gif 104 kg space probe is traveling at a speed of 12000 m/s through deep space. Retrorockets are fired along the line of motion to reduce the probe’s speed. The retrorockets generate a force of 3.00 http://www.webassign.net/images/multiply.gif 105 N over a distance of 2700 km. What is the final speed of the probe? m/s
9- Relative to the ground, what is the gravitational potential energy of a 55.0 kg person who is at the top of the Sears Tower, a height of 443 m above the ground? J
10- A 0.60 kg basketball is dropped out of the window that is 5.7 m above the ground. The ball is caught by a person whose hands are 1.1 m above the ground. How much work is done on the ball by its weight? J What is the gravitational potential energy of the basketball, relative to the ground when it is released? J What is the gravitational potential energy of the basketball when it is caught? J How is the change (PEf – PE0) in the ball’s gravitational potential energy related to the work done by its weight?