Solve the following problems on your own paper. Please:

• Show all work.
• Put a box around your final answer to each problem.
• Be sure proper significant figures (SF) used for all answers.
• Separate all solutions with a horizontal line on your paper.
• A random selection of four even problems will be graded for 25 points each.
• Solutions for suggested odd problems can be seen by following links.
• Solutions for even problems will be linked from this page after the due date.

Chapter 5

#4

The net work is just the total work done on the object, and it can be calculated either by summing the works done by all of the individual forces on the object or by calculating the change in kinetic energy of the object.

#18

See comment for problem #4. Here you will need to calculate the work done by each force since you don't know the change in kinetic energy.

#20

Be sure to work in mks units. The spring displacement is given in cm. For part (c), you may assume that the spring begins and ends its motion at rest.

#32

Assume only gravity does work in this problem.

#36

Similar to 32. Note that the mass of the block is irrelevant.

#42 #42

The plane is moving horizontally, so there is no change in potential energy. That means the change in mechanical energy is just equal to the change in kinetic energy. Mechnical energy is conserved if the change in mechanical energy is zero.

#44 #44

This is similar to #37, which we will do together in class.

#48

The final velocity here is zero, so you know the total work done because you know the change in kinetic energy. The only variable missing in the work-energy theorem is the displacement.

#50

Answer with 2 SF. The easiest way to find power here is to use the formula force * velocity.

#66 #66

Remember that on a vertical spring, we replace the normal force with the vertical spring force, so there is no normal force in this problem, just gravity and the spring forces acting. Note that gravity does do work as the spring is compressed by 9.00 cm (or 0.0900 m).

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Suggested odd problems:

C5, C6, C7, C9, C10, C11, C13, C15, #1, #2, #5, #6, #7, #8, #9, #10, #11, #13, #14, #15a #15b, #16, #17, #19, #23, #25, #27, #29a #29b, #33, #34, #35a #35b, #37, #38a #38b, #39, #40a #40b, #41, #45, #47, #51, #53, #54, #55, #58, #62, #68, #70, #71, #80a #80b, #89, #92