CHAPTER 8 – MACHINES
Unit 8.2 – Levers.
Remembering:
1. List three examples each of the class 1, class 2 and class 3 lever.
Class 1 = see saw. Class 2 = nut cracker. Class 3 = broom
2. Use a mathematical equation to state the principle of levers.
Effort x distance = load x distance.
3. State alternative names for a:
a. Fulcrum
Pivot.
b. Class 1 lever.
First order lever.
Understanding:
4. Define the terms:
a. Lever
A lever is just a solid object that is made to turn round a fulcrum. The load is placed on the lever and the effort causes it to turn.
b. Fulcrum
The point at which the lever turns.
c. Force multiplier
Force multipliers are classified as class 1 and 2 levers. You put in very little effort and the lever system multiplies so that lifting the heavier loads is easier.
d. Speed multiplier
A third class lever that increases an amount of force that is used to move/lift the load, also increases the speed.
5. Copy the following into your workbook and modify any incorrect statements to make them true:
a. All levers are force multipliers.
False = some levers are force multipliers.
b. The fulcrum of a lever is always somewhere in the middle.
False = the fulcrum can be in the middle of the lever but also at the end.
c. A golf club is an example of a force multiplier.
False = a golf club is an example of a speed multiplier.
d. A pivot is the same as a fulcrum.
True.
e. A speed multiplier is needed in most ball sports.
True.
6. Explain the advantage of using a class 3 lever in most ball sports.
The advantage of using a class 3 lever in ball sports is the distance the ball moves is large but the force we put on it is small.
7. Use a mathematical equation to explain how mechanical advantage is calculated for levers.
Mechanical advantage = load/effort = distance of effort from fulcrum/distance of load from fulcrum.
8. Describe how a greater mechanical advantage can be obtained when using a lever.
When using a lever a greater mechanical advantage obtained when the force applied is at the distant from the fulcrum.
9. A sword is an example of a class 3 lever. Explain why.
A sword is a class 3 lever because the load is at the tip of the blade, the force is placed through the handle and the fulcrum is further away from the tip.
10. You need to use a wheel brace to remove the nuts from a car wheel. A wheel brace is a spanner with a long arm. Propose a reason why the arm must be long.
The arm must be long so that the mechanical advantage is high.
Applying:
11. Done in hand-out
Analysing:
12. Done in hand-out
13. Done in hand-out
14. Contrast:
a. A force multiplier with a speed multiplier
A force multiplier applies a force over a distance so that the load can move a shorter distance. Whereas a speed multiplier applies a force that is close to the fulcrum to relocate the load in the same amount of time and a large distance.
b. Class 1 and 2 levers with a class 3 lever.
Class 1 and 2 levers are classified as force multipliers, but a class 3 lever is a speed multiplier.
Evaluating
15. Which class of levers is the most effective in listing a load? Justify your answer.
Because class 1 and 2 levers are practically the same I think that class as they both use force multipliers and their mechanical advantage is high.