Levers: Gaining More Leverage

1st, 2nd, & 3rd class LeversLevers: Gaining More Leverage1st class levers review:Look at the 1st class lever below.Identify the FELLAThink of at least 3 facts related to 1st class levers to share with the class

Discuss

1st class levers reviewF = fulcrumE = effortL = loadL = leverA = arm

1st Class Facts:

The fulcrum is always in the middle

Effort applied down, pulls the load up

Levers provide a mechanical advantage making work easier

The closer the load is to the fulcrum, the less effort it takes to lift the load

The further the effort is from the fulcrum, the easier it is to lift the loadLets look at more 1st Class leversExamples in strength trainingClass 1 - Seated dumbbell triceps extension

Try it! Place a heavy book in your arm and see your body work as a 1st class lever.

More classes of leversLook at the diagram below.What differences can you see between the different classes of levers?

Classes of LeversLevers can be set up in three basic ways

Class 1 fulcrum middleClass 2 load middleClass 3 effort middle

Remember: FLE = 123

2nd Class LeversCan you identify my FELLA?

How did you do?Class 2 - The fulcrum is at one end, the effort at the other end and the load lies between the effort and the fulcrum

Other examples of 2nd class leversExamples in strength trainingClass 2 - Standing heel lift

Try a standing heel lift and see your body work as a 2nd class lever!

Other examples of 2nd class leversClass 2 - Standing heel lift

Where is the load?Would you be able to locate the load in this illustration if it were not labeled?Why is the load sometimes difficult to identify in a class 2 lever?

RESISTANCE CAN BE CONSIDERED LOAD!!!

Remember the example of the oar from our 1st class levers

Lets explore this furtherLook at the example of the nutcracker

The weight of the nut IS NOT the load. (The nutcracker is not designed to move the nut around. It is designed to crush the nut)When you squeeze the ends of the lever, the jaws of the nutcracker push on the nutthe load is the resistance of the nut pushing back (= and opposite force anyone?)

But Miss Lamb, Im still confused???I can easily find the effort and fulcrum.Why are the arrows for the load pointing away from the hot dog?

[double 3rd class lever]

Effort is applied to the tongs causing a force against the hot dogthe hot dog resists by pushing back with an opposing = force.The load is the resistance pushed back by the hot dog.

Lets try to identify FELLA

Yes, paper can push against the blades!

Fireplace bellow anyone?

How will the 2nd class lever work?If the load and effort are found on the same side of the fulcrum, what does this mean will happen when we pull down?

Lets try itTake a look at the 2nd class lever.

What is happening?

The load will always pull down, but the effort will always have to pull up to counteract the load.

Note: Now that the scale is pulling up, you DO NOT need to add .5NLets discover more for ourselvesWork with your teacher to set up a 2nd class lever system.In this case, you will be measuring load (not resistance) and the effort that it takes to lift the loadExperiment. You will have to lift up with your spring scale, what will happen to the load?Will you have to add .5N to your calculations?What happens when you move the load closer to the fulcrum?

Complete the response sheet for more leverage!Stop here for today!

Lets review before we get started!Use the machines graphic organizer to draw an illustration of a 1st and 2nd class lever.Read page 10-11 in your Levers & Pulleys textbook.Answer the following questions:What is the mechanical advantage of a class 2 lever?What is the load in the bellows?How is the bellows like the nutcracker and garlic press?

Now we are going to explore the advantage rule for 2nd class levers. Experiment & DiscoverSet up your 2nd class lever. Set up your load from your assigned distance from the fulcrum.

Record your findings on the diagram in your packet.

Travel to the other desks in your row. Apply effort and record your findings on the diagram in your packet. When you are finished, return to your seat.

What do you find?

How are these classes different?Look at the position of the fulcrum in these pictures.What is different about the positions of the load and effort in a 2nd and 3rd class lever?

If the load and effort are found on the same side of the fulcrum, what does this mean will happen when we pull down?

3rd Class LeversClass 3 - The fulcrum is at one end, the load at the other end and the effort lies between the load and the fulcrumThe third class lever is the strangest ... and the one you use the most!Some 3rd class levers do not give any mechanical advantageSo why use them?The answer lies in the fact that the load moves in the same direction as the force you apply, which is convenient.

3rd Class LeversExamples:

3rd Class Lever Examples

They help us do work

3rd Class Lever ExamplesThey help us in sports!

Many sports are played with 3rd Class Levers!!!

3rd Class Lever ExamplesCan you identify my FELLA?

Examples in strength trainingClass 3 - Seated biceps curl

Try a seated biceps curl and see your body work as a3rd class lever!

More Examples of 3rd Class LeversDouble 3rd class levers

Levers ReviewCan you identify which class lever I am?

Lets reinforceRead pages 12-13 on levers in your Levers & Pulleys book

Be sure you can answer the following question:*What is the mechanical advantage of a class 3 lever?

Complete your graphic organizer by drawing a 3rd class lever picture

Look closer at everyday objects & determine their class