3.1.2 MOVEMENT ANALYSIS

Size: px

Start display at page:

Download "3.1.2 MOVEMENT ANALYSIS"

Peter Owen
6 years ago
Views:

1 3.1.2 MOVEMENT ANALYSIS Levers Mechanical Advantage

2 starter 1. Stick in your Assessment Grids from last lesson. NOT FOLDED 2. Fill out the score underneath the start of the lesson Start = % End = % 3. Correct any missing/incorrect answers in green pen

3 Learning objectives To be able to explain the mechanical advantage of each lever and related movements. To understand the 3 different lever class systems

4 Whiteboards Using the whiteboards you have been provided you need to answer the questions. When you have written your answer put your pen down and wait for the instruction to show.

5 1. Draw a linear diagram of a 1 st Class Lever System Effort Load Lever Arm Fulcrum

6 2. Draw a linear diagram of a 2 nd Class Lever System Load Lever Arm Effort Fulcrum

7 3. Draw a linear diagram of a 3 rd Class Lever System Load Lever Arm Fulcrum Effort

8 4. Which lever system is being used in picture below?

9 5. Which lever system is being used in picture below?

10 6. Which lever system is being used in picture below?

11 Mechanical advantage The relative efficiency of each of the lever systems is called the mechanical advantage. Effort Load Lever Arm Fulcrum How can the 1st class lever below be adjusted to increase or change how high the load can be propelled?

12 Mechanical advantage The efficiency of a working lever, calculated by: effort weight (resistance) arm

13 Mechanical advantage The body s levers can be made even more effective by using rackets, oars, paddles, sticks and bats.

14 Mechanical advantage These pieces of equipment increase the length of the resistance arm of the lever. This in turn increases the speed at the end of the lever.

15 Effects of a lever on the human body The extent to which a lever can increase speed depends upon the relative lengths of the resistance arm (RA) and effort arm (EA). Load Effort Lever Arm RA - Part of the lever between the fulcrum & the load Resistance Arm (RA) Fulcrum Effort Arm (EA) EA Part of the lever between the fulcrum & the effort

16 Resistance arm The resistance arm (RA) is the part of the lever between the fulcrum and the resistance. The longer the resistance arm, the greater speed can be generated. Load Effort Lever Arm Fulcrum Resistance Arm (RA)

17 Effort arm The effort arm (EA) is the distance between the fulcrum and the effort; the longer the effort arm the more force can be generated Load Effort Lever Arm Sporting implements are often used such as rackets or bats to increase the length of the effort arm which will increase the force that an object such as a ball is struck. Fulcrum Effort Arm (EA)

18 Effort arm However the optimal length of an implement should be determined by the strength of the person handling. e.g. junior tennis rackets have been designed for this purpose.

Mechanical disadvantage Most levers in the body are third class levers where the resistance arm is always greater than the effort arm (mechanical disadvantage).

19 Mechanical disadvantage Most levers in the body are third class levers where the resistance arm is always greater than the effort arm (mechanical disadvantage). The longer the resistance arm of the lever, the greater the speed at the end of it. So when bowling or passing a ball the performers arm should be fully extended to generate the most force and with the greatest speed.

20 Exam questions and resources

21 Apply it! What has stuck with you? Label the following levers components. Describe the 3 levers in the body (use diagrams to help illustrate your answer) Levers and mechanical advantage Explain the term mechanical advantage Which class of lever always has a mechanical disadvantage?

22 Practice it! Exam questions 1. Which one of the following describes a second class lever system? (1) A B C D The load is at the right-hand end of the lever The fulcrum is in the middle of the lever The load is in the middle of the lever The load and the fulcrum are at the same point on the lever 2. Label the lever system below (4) Lever class =

23 Practice it! Exam questions 3. Which one of these shows how to calculate the mechanical advantage of a lever? (1) A B C D Effort arm x weight (resistance) arm Effort arm weight (resistance) arm Effort arm + weight (resistance) arm Effort arm - weight (resistance) arm

24 Practice it! Exam questions 4. Analyse how the following parts of the lever system allow the weight trainer in Figure 5 to lift the weight. (i) Fulcrum (2) (ii) Effort (2)

25 Practice it! Exam questions 5. Figure 4 shows a basketball player jumping to execute a shot. Draw the lever system which operates at the ankle joint in the space below. Label the fulcrum, effort and load. (1)

26 Practice it! Marks Scheme: Effort Load 1. C Fulcrum 2. i) Third class lever 3. B 4. One mark for linking bone or muscle to component of lever system and one mark for linking this to its use in the biceps curl to lift the weight. For example: Fulcrum elbow is the fulcrum (1) which allows the arm to bend/flex (1) Effort biceps muscle provide the effort (1) which allows the weight lifter to lift the weight (1)

27 Practice it! Marks Scheme: 5. Award one mark for labelling the effort, load / resistance and fulcrum in the correct order.

2.1 Lever systems, examples of their use and the mechanical advantages they provide

2.1 Lever systems, examples of their use and the mechanical advantages they provide Learning objectives To understand the 3 different lever class systems To be able to describe the components of each lever