Work and Machines Study Guide

1. Work and MachinesStudy Guide

2. 1. The unit of work is called a Joule

3. 2. An ideal machine has an efficiency of100%

4. You do 1,200 J of work using a screwdriver. The screwdriver does 900 J of work on a screw. What is the efficiency of the screwdriver?75%

5. A machine can make work easier byChanging the direction of force needed to accomplish a task.

6. An ax, a zipper, and a front tooth are examples of a simple machine called a Wedge

7. You divide the radius of a wheel by the radius of an axle. What are you calculating?The ideal mechanical advantage of a wheel and axle

8. A car’s steering wheel is an example of a simple machine called a(n)_______.Wheel and axle

9. The fixed point that a lever rotates around is called a(n) Fulcrum

10. Compound machines are Combination of simple machines

11. When you bend your arm at the elbow, the fulcrum is at yourElbow

12. In order to do work on an object, the object must _______ as a result of your force.move some distance

13. A machine’s __________ is the number of times a force exerted on a machines is multiplied by the machine.mechanical advantage

14. In a screwdriver, the handle is the wheel and the shaft is the _______.axle

15. Muscles are attached to bones by ___________.tendons

16. The more efficient a machine is, the closer the actual mechanical advantage is to the _______.Ideal mechanical advantage

17. A machine does not decrease the amount of work you do.True

18. An inclined plane wrapped around a central cylinder is a screw.True

19. A rope wrapped around a grooved wheel is a pulley.True

20. A single fixed pulley, such as a flagpole, changes the direction of the input force.True

21. When you bite into a sandwich, your front teeth act as wedges.True

22. (5 points) List the six types of simple machines and give an example of how you would use each one in your daily life.

23. Screw – jar lidinclined plane – wheelchair ramppulley – flagpolewedge-sharp knifelever – baseball batwheel and axle - bicycle