Inquiry Questions/Content
Investigation 1: Levers
Part 1:
1. Levers and pulleys are examples of simple machines .
2. What are the four parts of a lever system?
- fulcrum
- load
- effort
- lever arm
3. In what ways can a lever provide an advantage?
- lift or move a load
- less effort
- easier to lift a load
4. How can you measure the advantage provided by a lever?
You can measure the advantage by using a spring scale.
5. What is the relationship between the load and effort that gives a lever user the greatest advantage (makes it the easiest to lift the load)?
In a lever system the farther from the fulcrum the effort is applied, the greater advantage to the lever user.
Part 2:
1. How much force (effort) is needed to lift the load (the black weight)?
The force needed to lift the load is 2.4N.
2. If a spring scale pulls with a force of 0.5 N, what is the total pull applied to the lever system?
The total pull is l.0 N.
3. What is the relationship between the position of the effort and the amount of effort needed to lift the load?
The closer the load is to the fulcrum, the less effort is needed to lift the load.
The farther the load is to the fulcrum, the more effort is needed to lift the load.
4. When the load is at a constant position on the lever arm, how can you make it easier to lift the load?
The farther the effort is to from the fulcrum, the easier it is to lift the load.
5. What is the difference between the weight of the load and the amount of effort needed to lift it?
The weight of the load remains constant. The effort needed to lift the load varies depending on where the effort is applied on the lever arm.
Part 3:
1. What is the difference between the location of the load on the lever system and the effort it takes to move it?
The effort needed to lift the load decreases as the load gets closer to the fulcrum. The effort increases as the load gets farther from the fulcrum.
Inquiry Questions/Content
Investigation 2: More Leverage
Part 1:
1. How many different ways can levers be set up? Diagram and label each kind of lever.
Levers can be set up in three basic ways. They are called class 1, class 2, and class 3.
2. Describe the symbols used to diagram levers.
Part 2:
3. How can we record information about lever design?
A diagram uses a system of symbols and conventions to communicate information about lever designs.
Part 3:
4. Where are levers found in everyday use?
Many common tools use levers: scissors, pliers, bottle openers, hammers, wheelbarrows, and brooms, to name a few.
5. What happens to the effort required to lift the load in a class-1 lever, class-2 lever, and a class-3 lever?
Effort is reduced as the load moves closer to the fulcrum.
Inquiry Questions/Content
Investigation 3: Pulleys
Part 1:
1. Single means one pulley wheel .
2. Fixed means attached .
3. What are the 2 advantages that pulleys give?
- mechanical advantage (reduced effort)
- directional advantage (change the direction that the effort is applied)
4. When do you add 0.5N to a scale reading?
Add 0.5N to the scale reading only when pulling down.
5. Can a pulley be used to lift a load?
A single pulley can be set up as a fixed pulley or a movable pulley to lift a load.
6. Do single-pulley systems provide advantage?
Single fixed pulleys change the direction of effort. Single movable pulleys reduce the effort needed to lift the load.
Part 2:
1. What are the 6 simple machines?
- levers
- pulleys
- inclined plane
- wedge
- screw
- wheel and axle
2. What is a simple machine?
Simple machines provide mechanical or other advantage
3. Is there an advantage to using two pulleys at the same time?
Two pulleys can provide greater mechanical advantage than one when lifting a load
Inquiry Questions/Content
Investigation 4: Pulleys at Work
Part 1:
1. What is the relationship between the number of ropes supporting the load in a pulley system and the effort required to lift the load?
The greater the number of ropes supporting the load, the less the effort needed to lift the load.
2. What do you need to know in order to predict how much effort will be needed to lift a load with a pulley system?
The effort needed to lift a load can be predicted from the weight of the load and the number of ropes supporting the load.
Part 2:
1. How does the expression “You never get something for nothing” apply to pulley systems?
The benefits gained by using simple machines are always balanced by costs. When the benefits outweigh the costs, the machine is a useful tool.
Kind of Pulley System / Number of Ropes Supporting the Load / EFFORT =Load ÷
Number of Ropes Supporting the Load / DISTANCE EFFORT MOVED =
Distance Load Moved x
Number of Ropes Supporting the Load / DISTANCE LOAD MOVED =
Distance Effort Moved ÷ Number of Ropes Supporting the Load