Lesson 2.5: Levers in Your Body

Your body has many levers.  Each of your fingers has three levers in it.  You can see this easily when you look at your finger and try to bend it at each of the three joints. 

Read Your Body Has Levers, Too on page 138 in your textbook. Then, answer the following.

Question 1. Which two classes of levers are found in your arm?

Question 2. Which class of lever is used in your arm when you lift an object?

Question 3. Which class of lever is used in your arm when you pull down on an object?

Question 4. When a third class lever is used in your arm, which muscle is being used?

Question 5. When a first class lever is used in your arm, which muscle is being used?

 

Then, return here to continue this lesson.

 

 

Levers are also classed as force or distance multipliers. 

Force multipliers are used to enable small forces to move heavy loads.  If you have ever jacked up a car to change a tire, you have used a force multiplier.  Imagine trying to lift the car off  the ground without using a machine.   Each time you move the lever arm of the jack a long distance, you raise the car only a centimetre or two. 

Distance multipliers are used to make small loads move faster. 

Read Distance Multipliers and Force Multipliers on pages 138 and 139 in your textbook.

Question 6. List five distance multipliers that were discussed.

Question 7. What is an example of a force multiplier? 

Question 8. Why can you not use a third class lever as a force multiplier?

  

Then, return here to continue this lesson.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 1. Which two classes of levers are found in your arm?

The two classes of levers found in your arm are first class and third class.

Question 2. Which class of lever is used in your arm when you lift an object?

Your arm uses a third class lever to lift an object.  A third class lever has the effort between the load and the fulcrum.

Question 3. Which class of lever is used in your arm when you pull down on an object?

Your arm uses a first class lever to pull down on an object.  A first class lever has the fulcrum between the load and the effort .

Question 4. When a third class lever is used in your arm, which muscle is being used?

When a third class lever is used in your arm, the bicep is being used.

Question 5. When a first class lever is used in your arm, which muscle is being used?

When a first class lever is used in your arm, the tricep is being used?

 

Click to return to where you left off in this lesson.

 

 

 

 

 

 

 

 

 

 

 

Answers to Questions:

Question 6. List five distance multipliers that were discussed.

The five distance multipliers that were mentioned in the text were the following:
-  fishing rod
-  hockey stick
-  tennis racket
-  axe
-  mallets (or hammer used to pound a nail)

Question 7. What is an example of a force multiplier? 

The example that was discussed on this page was a car jack.

Question 8. Why can you not use a third class lever as a force multiplier?

It is not possible to use a third class lever as a force multiplier because the effort is always between the fulcrum and the load.

 


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