Question
Gizmo Warm-up
The Pulley Lab Gizmo demonstrates why pulleys are useful for lifting loads. To begin, check that the Gizmo has the following settings:
● The Pulley configuration is 1 fixed.
● Ideal pulleys (0.0 N) is selected.
● The Weight is 50 N (50 newtons), and the Efficiency is 100%.
To apply an input force, drag the Input force spring balance to the right. Slowly increase the force until the 50-N load begins to rise.
1. What is the minimum force required to lift a 50-N load with one fixed pulley?
2. Change the Pulley configuration to 1 fixed, 1 moveable. As you did before, slowly drag the Input force balance to the right until the load begins to lift.
A. What force is required to lift a 50-N load with this pulley system?
B. What is one advantage of using a pulley system?
Activity A:
Mechanical advantage Get the Gizmo ready:
● Select the 1 fixed pulley configuration.
● Set the Weight to 60 N and Efficiency to 100%.
● You will need a calculator for this activity.
Introduction: A pulley is an example of a simple machine. Many simple machines are useful because they allow the user to lift a heavy weight using less force than it would take to lift the weight directly. The mechanical advantage of the machine is a measure of this benefit.
Question: What is the mechanical advantage of each pulley system?
1. Predict: How will adding more pulleys affect the input force needed to lift the load?
2. Gather data: With the Weight set to 60 N and the Efficiency set to 100%, find the minimum input force needed to lift the load with each system. Fill in the table below. Include units.
Pulley system Weight (N) Minimum input force (N)
1 fixed 60 N
1 fixed, 1 moveable 60 N
2 fixed, 2 moveable 60 N
3 fixed, 3 moveable 60 N
3. Summarize: How does the minimum input change as you add more pulleys to the system?
4. Analyze: Compare the input force to the number of pulleys in each system. Do you see a pattern? If so, describe it:
5. Apply: How much force do you think would be needed to lift a 100-N load with a pulley system composed of
two fixed and two moveable pulleys?
Check your answer with the Gizmo. How much force was actually needed?
6. Calculate: The mechanical advantage of a pulley system is equal to the output force (Fout) divided by the input force (Fin):
The input force and output force for each pulley system is shown in the bottom-right corner of the Gizmo. Use the Gizmo to find the input force and output force for each pulley system. In each case, use the same input force that you used to lift the 60-N load.
Pulley system Input force (N) Output force (N) Mechanical advantage
1 fixed
1 fixed,
1 moveable
2 fixed,
2 moveable
3 fixed,
3 moveable
7. Make a rule: How is the mechanical advantage related to the total number of pulleys in the pulley system?
8. Apply: Imagine a pulley system with four fixed and four moveable pulleys.
A. What would be the mechanical advantage of this system?
B. Using this system, how much input force would be needed to lift a 500-N load?
9. Think and discuss: So far, you’ve been working with an “ideal” pulley system. How do you think real pulley systems are different, and how would that affect the mechanical advantage of real pulley systems?
The Pulley Lab Gizmo demonstrates why pulleys are useful for lifting loads. To begin, check that the Gizmo has the following settings:
● The Pulley configuration is 1 fixed.
● Ideal pulleys (0.0 N) is selected.
● The Weight is 50 N (50 newtons), and the Efficiency is 100%.
To apply an input force, drag the Input force spring balance to the right. Slowly increase the force until the 50-N load begins to rise.
1. What is the minimum force required to lift a 50-N load with one fixed pulley?
2. Change the Pulley configuration to 1 fixed, 1 moveable. As you did before, slowly drag the Input force balance to the right until the load begins to lift.
A. What force is required to lift a 50-N load with this pulley system?
B. What is one advantage of using a pulley system?
Activity A:
Mechanical advantage Get the Gizmo ready:
● Select the 1 fixed pulley configuration.
● Set the Weight to 60 N and Efficiency to 100%.
● You will need a calculator for this activity.
Introduction: A pulley is an example of a simple machine. Many simple machines are useful because they allow the user to lift a heavy weight using less force than it would take to lift the weight directly. The mechanical advantage of the machine is a measure of this benefit.
Question: What is the mechanical advantage of each pulley system?
1. Predict: How will adding more pulleys affect the input force needed to lift the load?
2. Gather data: With the Weight set to 60 N and the Efficiency set to 100%, find the minimum input force needed to lift the load with each system. Fill in the table below. Include units.
Pulley system Weight (N) Minimum input force (N)
1 fixed 60 N
1 fixed, 1 moveable 60 N
2 fixed, 2 moveable 60 N
3 fixed, 3 moveable 60 N
3. Summarize: How does the minimum input change as you add more pulleys to the system?
4. Analyze: Compare the input force to the number of pulleys in each system. Do you see a pattern? If so, describe it:
5. Apply: How much force do you think would be needed to lift a 100-N load with a pulley system composed of
two fixed and two moveable pulleys?
Check your answer with the Gizmo. How much force was actually needed?
6. Calculate: The mechanical advantage of a pulley system is equal to the output force (Fout) divided by the input force (Fin):
The input force and output force for each pulley system is shown in the bottom-right corner of the Gizmo. Use the Gizmo to find the input force and output force for each pulley system. In each case, use the same input force that you used to lift the 60-N load.
Pulley system Input force (N) Output force (N) Mechanical advantage
1 fixed
1 fixed,
1 moveable
2 fixed,
2 moveable
3 fixed,
3 moveable
7. Make a rule: How is the mechanical advantage related to the total number of pulleys in the pulley system?
8. Apply: Imagine a pulley system with four fixed and four moveable pulleys.
A. What would be the mechanical advantage of this system?
B. Using this system, how much input force would be needed to lift a 500-N load?
9. Think and discuss: So far, you’ve been working with an “ideal” pulley system. How do you think real pulley systems are different, and how would that affect the mechanical advantage of real pulley systems?
Answers
GPT-4o mini
To answer your questions, let's go through them step by step, assuming you will run the experiments using the Gizmo.
### Warm-up Questions:
1. **What is the minimum force required to lift a 50-N load with one fixed pulley?**
- **Answer**: The minimum force required is 50 N. A fixed pulley does not provide mechanical advantage; it simply redirects the force needed.
2. **Change the Pulley configuration to 1 fixed, 1 moveable.**
- A. **What force is required to lift a 50-N load with this pulley system?**
- **Answer**: The required input force for a movable pulley system is typically half the weight. Thus, it should be 25 N.
- B. **What is one advantage of using a pulley system?**
- **Answer**: One advantage is that it allows you to lift heavier loads with less input force, making it easier to move heavy objects.
### Activity A:
1. **Predict**: How will adding more pulleys affect the input force needed to lift the load?
- **Answer**: Adding more pulleys will decrease the input force needed to lift the load because each additional pulley adds mechanical advantage.
2. **Gather data**: Fill in the table below.
| Pulley System | Weight (N) | Minimum Input Force (N) |
|----------------------------|-------------|--------------------------|
| 1 fixed | 60 N | 60 N |
| 1 fixed, 1 moveable | 60 N | 30 N |
| 2 fixed, 2 moveable | 60 N | 15 N |
| 3 fixed, 3 moveable | 60 N | 10 N |
3. **Summarize**: How does the minimum input change as you add more pulleys to the system?
- **Answer**: As more pulleys are added, the minimum input force required decreases. This is due to the mechanical advantage gained by the pulleys.
4. **Analyze**: Compare the input force to the number of pulleys in each system. Do you see a pattern?
- **Answer**: Yes, there is a clear pattern. The more pulleys you have (fixed and movable), the less input force required to lift the same weight because the mechanical advantage increases.
5. **Apply**: For a pulley system composed of two fixed and two moveable pulleys lifting a 100-N load, the estimated required input force would be 25 N. Check your answer with the Gizmo.
- **Check** the actual force needed. (If this part were done in the Gizmo, you'd record the value shown).
6. **Calculate**: Fill in the table for mechanical advantage based on the recorded input and output forces.
| Pulley System | Input Force (N) | Output Force (N) | Mechanical Advantage |
|----------------------------|------------------|-------------------|------------------------|
| 1 fixed | 60 N | 60 N | 1 |
| 1 fixed, 1 moveable | 30 N | 60 N | 2 |
| 2 fixed, 2 moveable | 15 N | 60 N | 4 |
| 3 fixed, 3 moveable | 10 N | 60 N | 6 |
7. **Make a rule**: How is the mechanical advantage related to the total number of pulleys in the pulley system?
- **Answer**: The mechanical advantage increases with the number of pulleys in the system. The number of movable pulleys typically contributes directly to mechanical advantage.
8. **Apply**:
A. For a system with four fixed and four moveable pulleys, the mechanical advantage would be 8 (4 from fixed and 4 from movable pulleys).
B. To lift a 500-N load, the input force would be 62.5 N since 500 N / 8 = 62.5 N.
9. **Think and discuss**: How do you think real pulley systems are different, and how would that affect the mechanical advantage of real pulley systems?
- **Answer**: Real pulley systems experience friction and other inefficiencies, which would reduce their mechanical advantage compared to ideal systems. Factors such as material weight, friction in the pulleys, and alignment can all reduce the effective force you can apply to lift the weight.
Feel free to adjust the answers based on specific results you observe from the Gizmo or clarify any specific doubts you may have!
### Warm-up Questions:
1. **What is the minimum force required to lift a 50-N load with one fixed pulley?**
- **Answer**: The minimum force required is 50 N. A fixed pulley does not provide mechanical advantage; it simply redirects the force needed.
2. **Change the Pulley configuration to 1 fixed, 1 moveable.**
- A. **What force is required to lift a 50-N load with this pulley system?**
- **Answer**: The required input force for a movable pulley system is typically half the weight. Thus, it should be 25 N.
- B. **What is one advantage of using a pulley system?**
- **Answer**: One advantage is that it allows you to lift heavier loads with less input force, making it easier to move heavy objects.
### Activity A:
1. **Predict**: How will adding more pulleys affect the input force needed to lift the load?
- **Answer**: Adding more pulleys will decrease the input force needed to lift the load because each additional pulley adds mechanical advantage.
2. **Gather data**: Fill in the table below.
| Pulley System | Weight (N) | Minimum Input Force (N) |
|----------------------------|-------------|--------------------------|
| 1 fixed | 60 N | 60 N |
| 1 fixed, 1 moveable | 60 N | 30 N |
| 2 fixed, 2 moveable | 60 N | 15 N |
| 3 fixed, 3 moveable | 60 N | 10 N |
3. **Summarize**: How does the minimum input change as you add more pulleys to the system?
- **Answer**: As more pulleys are added, the minimum input force required decreases. This is due to the mechanical advantage gained by the pulleys.
4. **Analyze**: Compare the input force to the number of pulleys in each system. Do you see a pattern?
- **Answer**: Yes, there is a clear pattern. The more pulleys you have (fixed and movable), the less input force required to lift the same weight because the mechanical advantage increases.
5. **Apply**: For a pulley system composed of two fixed and two moveable pulleys lifting a 100-N load, the estimated required input force would be 25 N. Check your answer with the Gizmo.
- **Check** the actual force needed. (If this part were done in the Gizmo, you'd record the value shown).
6. **Calculate**: Fill in the table for mechanical advantage based on the recorded input and output forces.
| Pulley System | Input Force (N) | Output Force (N) | Mechanical Advantage |
|----------------------------|------------------|-------------------|------------------------|
| 1 fixed | 60 N | 60 N | 1 |
| 1 fixed, 1 moveable | 30 N | 60 N | 2 |
| 2 fixed, 2 moveable | 15 N | 60 N | 4 |
| 3 fixed, 3 moveable | 10 N | 60 N | 6 |
7. **Make a rule**: How is the mechanical advantage related to the total number of pulleys in the pulley system?
- **Answer**: The mechanical advantage increases with the number of pulleys in the system. The number of movable pulleys typically contributes directly to mechanical advantage.
8. **Apply**:
A. For a system with four fixed and four moveable pulleys, the mechanical advantage would be 8 (4 from fixed and 4 from movable pulleys).
B. To lift a 500-N load, the input force would be 62.5 N since 500 N / 8 = 62.5 N.
9. **Think and discuss**: How do you think real pulley systems are different, and how would that affect the mechanical advantage of real pulley systems?
- **Answer**: Real pulley systems experience friction and other inefficiencies, which would reduce their mechanical advantage compared to ideal systems. Factors such as material weight, friction in the pulleys, and alignment can all reduce the effective force you can apply to lift the weight.
Feel free to adjust the answers based on specific results you observe from the Gizmo or clarify any specific doubts you may have!