Levers

1. Levers Function/Purpose Types Long Levers Shorts Levers Advantages in Sports

2. What are levers? • Levers are used to apply forces. • They consist of a: • Pivot point [fulcrum] (the point about which the lever rotates) • A load (the force applied by the lever system) • Effort (the force applied by the user of lever system)

3. What are levers? • Levers help apply large amounts of force with less effort Eg; levering the lid off a tin with a screwdriver. • Levers also help move a LOAD at greater speeds. • The amount of leverage a person has depends on the length of their lever arm (e.g their body i.e the length of their arms and legs).

4. Types of Levers • There are 3 types of levers: • First Class, Second Class and Third Class. • They are classified depending on where the fulcrum, load and forces are applied. • The most common in the body is the Third Class Lever.

5. Class 3 Levers

6. Levers in the Human Body • The human body is built around a sturdy frame called the skeleton. Muscles are attached to the skeleton and generate movement. Many levers exist within the skeletal structure. • Nature has designed the human body for movement rather than maximising force.

7. Levers in Action • http://www.dynamicscience.com.au/tester/solutions/hydraulicus/humanbody.htm

8. Example: The Elbow • Fulcrum or pivot point in the body is at the joint i.e. elbow • The load is whatever maybe in the hand i.e. 5kg dumbbell. • The effort is the strength applied by the bicep and tricep muscle pairing when performing flexion and extension at the elbow. This occurs at the point where the tendons attach the muscles to the skeletal structure.

9. Long Levers • The longer the lever the greater the speed generated at the end of the lever and therefore the more force applied. • This is because the longer lever has a greater range of motion to travel through and therefore more time to gain speed. • This is beneficial for running, throwing, striking, kicking. • What are some examples in sport of where longer levers are an advantage and why?

11. Short Levers • Short levers can move with less force but will get to the end result quicker. • This is beneficial for moving body parts quickly and applying strength for pushing, pulling and lifting objects. • What are some examples in sport of where shorter levers are an advantage and why?

13. However! • When you relate this to a sport eg: Kickboxing, the force applied is also dependant on the size of the person ie; how strong they are or how much weight they carry behind their lever!

14. Question • Identify the fulcrum, load and effort in the pictures below?

15. Group Brainstorm • Short people are stronger than taller people. • In groups of 4, decide if you are in support of or are against this argument. • Write down 3 points to support your answer. • Use your knowledge of levers and the information in this ppt to help you decide.

16. Answer • Much of this comes down to what strength is – how short levers and long levers can be used to generate force for human movement. • Short people have shorter levers because their body segments (eg;upper arms) are of a shorter length, therefore they can apply more force with those levers. Wrestlers and power builders are typically short and have well built physiques. • Tall people could be stronger than short people when applying force at high speeds (such as swinging a tennis racket at a ball) – the end of their levers (such as their arms) is travelling at a greater momentum and can therefore produce more speed onto the object (the ball) which is being hit.