1. Sci. 4-2
What is a Machine?
Pages 92-97

2. A. Machine- a device that helps make work easier by changing the size or direction of a force.

3. B. The work you do on a machine is called work input
B. The work you do on a machine is called work input. The work done by the machine is called work output.

4. C. Work output can NEVER be greater than work input.
(W = F x d)

5. D. Force or distance can increase but not together
D. Force or distance can increase but not together. When one increases, the other must decrease.

6. E. Mechanical Advantage- a number that tells how many times a machine multiplies force.

7. Mechanical Advantage Formula-
Mechanical Advantage (MA) = output force/input force
(MA) = Output force
Input force

8. G. If the mechanical advantage is less than 1, that means that the input force is greater than the output force

9. H. Mechanical Efficiency- is a comparison of a machine’s work output with the work input. Shown as a percent (%).

10. Work output is always less than work input because the machine must overcome friction.
J. No machine is 100% efficient because some of the work input is used to overcome friction.