1. Chapter 4: Work & Simple Machines
Review PowerPoint

2. Describe the six simple machines.
Inclined plane: flat sloped surface
Wedge: Moveable inclined plane
Screw: Inclined plane wrapped around a post
Lever: Rod or plank that pivots
Wheel & axle: Two circular object that are attached and rotate together
Pulley: Grooved wheel with a rope or chain wrapped around it

3. How are the simple machines useful?
Inclined plane: decreases force, increases distance
Wedge: MA increases as it becomes longer and thinner
Screw: Changes direction of input force
Lever: MA changes based on location of fulcrum
Wheel & axle: MA is usually greater than one
Pulley: Changes direction of force

4. Give an example of each simple machine.
Inclined plane: Ramp
Wedge: Axe
Screw: Top of water bottle
Lever: Baseball bat
Wheel & axle: Doorknob
Pulley: Flagpole

5. What is power?
Rate at which work is done

6. What is a compound machine? Give an example.
Two or more simple machines that work together
Lawnmower is made up of a lever, wheel and axle, and a wedge.

7. What is mechanical advantage?
MA is the amount by which a machine multiplies an input force.

8. What is efficiency?
The work output of a machine divided by the work input.

9. Contrast input and output force.
Input force is what you apply to a simple machine.
Output force is what you overcome when using a simple machine.

10. What is work?
Work depends on the force applied to the object and the distance the object is moved.

11. Why is it important for tires on a car be inflated the proper amount?
Low air increases the friction between the tires and the road. This reduces the efficiency.

12. How is oil helpful between surfaces?
Oil fills the gaps between surfaces and prevents many spots on the surfaces from coming in contact, reducing the force of friction.

13. Know how to calculate work.
Work = Force x distance
Measured in Joules

14. Know how to calculate power.
Power = Work/Time
Measure in Watts

15. Know how to calculate Mechanical Advantage.
MA = Output force/Input force