What is purpose of a machine?

1. What is purpose of a machine? • To allow you to use less force in order to make work easier.

2. What is an inclined plane? A simple machine with no moving parts. It is simply a straight slanted surface. ( Example- a ramp.)

3. Measuring Work Lab • From the Inclined Plane lab we will use the following formula: Load FORCE x Load DISTANCE = Load WORK HINT – A flashcard worthy equation above

4. Diagram of Inclined Plane The effort force is the amount of force it takes to pull something up a ramp. It is measured with a spring scale. Effort force x effort distance = effort work Load distance = vertical Load Force = Distance up the ramp

5. How an inclined plane works • An inclined plane allows you to increase the effort distance while decreasing the effort force. • When the angle of the ramp increases…. The effort distance decreases The effort force increases The amount of work STAYS THE SAME! LOAD WORK should equal EFFORT WORK!!!!

6. THERE IS NOTHING TO WRITE DOWN FOR THIS SLIDE Load force times load distance = Load work Load force (weight of an object) Load distance is the distance you will raise the object

7. Amount of work • THE AMOUNT OF WORK REMAINS THE SAME FOR BOTH EFFORT AND LOAD. • Effort Work should equal Load Work • (FxD) (FxD)

8. Examples of INCLINED PLANES Which of the following do you think are modified inclined planes: pulley Wedge Lever Screw Wheel & Axle Gear

9. What are some examples of inclined planes that are used to make effort force easier? • Which do you think would be easier to screw into a board? (least EFFORT FORCE from you) • A screw with many turns (longer distance used) • A screw with few turns (shorter distance used) Circle your choice on your notes

10. Which would require less EFFORT FORCE • As you increase the distance covered you are decreasing the amount of force required. • So the screw with MANY TURNS or a longer spiral will require the least EFFORT FORCE…

11. Define / Describe WORK • Work occurs when a force is applied to move an object a DISTANCE • Work is done when a force causes an object to move in the direction that the force is applied. • The formula for work is: W = F X D • If there is no movement, there is no work

12. How is work done • Two things must happen for WORK to be done. What are they? • 1. A FORCE must be applied to an object • 2. The object must move in the SAME direction as the FORCE applied.

13. How do machines make work easier? • 1. They can change the amount of force • 2. They can change the direction of the force • Remember that work=force x distance

14. How do machines make work easier? Any change in the size of the distance changes the force. No machine can increase both force and distance. Simple machines can multiply force which decreases distance the load moves. (lever) Or they can multiply the distance which decreases force. (inclined plane) Or, they leave force and distance alone but change the direction in which the load moves. (pulley)

15. What are the 3 types of simple machines? • There are three basic simple machines: -the lever, the pulley, and the inclined plane • The wheel and axle, the wedge, and the screw and gear are modifications of the three simple machines.

16. Describe LEVER A simple machine made with a rigid bar free to pivot (move) around a fixed point called a fulcrum

17. Describe the 3 types of levers: • A first class lever is like a teeter-totter or see-saw. One end will lift an object (child) up just as far as the other end is pushed down. • A second class lever is like a wheel barrow. The long handles of a wheel barrow are really the long arms of a lever. • A third class lever is like a fishing pole. When the pole is given a tug, one end stays still but the other end flips in the air catching the fish.

18. Effort and Load

19. Describe PULLEYS A pulley is a simple machine made with a rope, belt or chain wrapped around a grooved wheel. A pulley works two ways. The pulley can change the direction of a force. The pulley can change the amount of force.

20. Diagrams of Pulleys Fixed pulley: http://www.smartown.com/sp2000/machines2000/pulley2.htm Movable Pulley: http://www.smartown.com/sp2000/machines2000/pulley3.htm

21. What are the types of pulleys? • Fixed pulley Does not multiply force. Changes the direction of the effort force. Mechanical advantage is equal to one. • Movable pulley Multiplies effort force but cannot change direction of the effort force. Mechanical advantage is the effort distance divided by the resistance distance. • Pulley system A combination of fixed and movable pulleys. Mechanical advantage is equal to the number of supporting ropes.

22. How does a fixed pulley work? A fixed pulley changes the direction of the applied force. ( Ex. Raising a flag )

23. How does a moveable pulley work? A movable pulley is attached to the object that is being moved.

24. What is mechanical advantage? The number of times a machine multiplies the effort force. The MA (mechanical advantage) is the Load Force moved divided by the Effort force used. What is a compound machine? A machine made up of TWO or more simple machines.

25. What is a wheel and axle? A wheel and axle is a modification of a pulley. A wheel is fixed to a axle. The wheel and axle must move together to be a simple machine. Sometimes the wheel has a crank or handle on it. Examples of wheel and axles include roller skates and doorknobs.

26. Diagram of Wheel & Axle http://www.smartown.com/sp2000/machines2000/wheelandaxle.htm

27. What is a wedge? A wedge is a modification of an inclined plane that moves . It is made of two inclined planes put together. Instead of the load being moved up an inclined plane, the inclined plane moves the load.

28. Diagram of Wedge www.angelfire.com/scifi/dschlott/ simplemachines.html

29. What is a screw? A screw is a simple machine that is like an inclined plane. It is an inclined plane that wraps around a cylinder.