http://www.ck12.org Chapter 16. Work and Machines
Lesson Review Questions
Recall
- What is a machine?
- Identify three different ways that machines may change force.
- What does efficiency measure?
- Define actual mechanical advantage.
- How does ideal mechanical advantage differ from actual mechanical advantage? How is ideal mechanical
advantage calculated?
Apply Concepts
- In the picture below, a screwdriver is being used to pry the lid off a paint can. The tip of the screwdriver
is resting on the top edge of the can. When the handle of the screwdriver is pushed down, the tip of the
screwdriver pushes up on the edge of the lid. Draw a simple labeled sketch to show the input and output
distances involved in this work. How does the input distance compare with the output distance? Is the ideal
mechanical advantage of the screwdriver greater than, less than, or equal to 1? - Assume that a machine puts out 8000 joules of work when the user puts in 10,000 joules of work. What is the
efficiency of the machine?
Think Critically
- The mechanical advantage of a machine is related to how it changes force. Explain this relationship.
Points to Consider
The canoe paddles, nutcracker, and hammer that you read about in this lesson have something in common. All three
are examples of a type of simple machine called a lever.
- Based on these three examples, how would you describe a lever?
- How do you think a lever changes the force applied to it?