Question
A moving company wants to lift a piano to the second story of a house and has these three pulley set ups to choose from (the piano would replace the weight pictured). Which would be the best choice and why?
(1 point)
Responses
Choice B would be the best, because you are pulling upwards using half of the force, so it would be easier.
Choice B would be the best, because you are pulling upwards using half of the force, so it would be easier.
Choice A would be the best because the pull motion is downward he will only use 1/2 of the force, so that will be easier.
Choice A would be the best because the pull motion is downward he will only use 1/2 of the force, so that will be easier.
Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.
Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.
Either A or B because the force will be the same (half) and the amount of rope pulled is the same and the directions does not matter.
Either A or B because the force will be the same (half) and the amount of rope pulled is the same and the directions does not matter.
Question 2
A man is using a pulley to raise a weight. He is applying 45 joules of energy to pull on that rope and 44.325 joules of energy are being used to lift the weight. What is the efficiency of the pulley?
(1 point)
Responses
98.5%
98.5%
1.015%
1.015%
98.325 joules
98.325 joules
.675 Joules
(1 point)
Responses
Choice B would be the best, because you are pulling upwards using half of the force, so it would be easier.
Choice B would be the best, because you are pulling upwards using half of the force, so it would be easier.
Choice A would be the best because the pull motion is downward he will only use 1/2 of the force, so that will be easier.
Choice A would be the best because the pull motion is downward he will only use 1/2 of the force, so that will be easier.
Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.
Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.
Either A or B because the force will be the same (half) and the amount of rope pulled is the same and the directions does not matter.
Either A or B because the force will be the same (half) and the amount of rope pulled is the same and the directions does not matter.
Question 2
A man is using a pulley to raise a weight. He is applying 45 joules of energy to pull on that rope and 44.325 joules of energy are being used to lift the weight. What is the efficiency of the pulley?
(1 point)
Responses
98.5%
98.5%
1.015%
1.015%
98.325 joules
98.325 joules
.675 Joules
Answers
GPT-4o mini
### Question 1
For the first question regarding the pulley setups for lifting a piano, the best choice would be:
**Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.**
This choice accurately reflects the fundamental purpose of a pulley system, which is to change the direction of force and potentially reduce the amount of force needed to lift an object, even if it requires pulling more rope.
---
### Question 2
For the second question on efficiency:
Efficiency can be calculated using the formula:
\[
\text{Efficiency} = \left( \frac{\text{Useful Output Energy}}{\text{Input Energy}} \right) \times 100
\]
In this case:
- Useful Output Energy = 44.325 joules (energy used to lift the weight)
- Input Energy = 45 joules (energy applied to pull the rope)
Now plug in the values:
\[
\text{Efficiency} = \left( \frac{44.325}{45} \right) \times 100 \approx 98.5\%
\]
Thus, the answer is:
**98.5%**
For the first question regarding the pulley setups for lifting a piano, the best choice would be:
**Choice C because the pulley changes the directions of the pull and reduces the amount of force needed, even though the rope is pulled longer.**
This choice accurately reflects the fundamental purpose of a pulley system, which is to change the direction of force and potentially reduce the amount of force needed to lift an object, even if it requires pulling more rope.
---
### Question 2
For the second question on efficiency:
Efficiency can be calculated using the formula:
\[
\text{Efficiency} = \left( \frac{\text{Useful Output Energy}}{\text{Input Energy}} \right) \times 100
\]
In this case:
- Useful Output Energy = 44.325 joules (energy used to lift the weight)
- Input Energy = 45 joules (energy applied to pull the rope)
Now plug in the values:
\[
\text{Efficiency} = \left( \frac{44.325}{45} \right) \times 100 \approx 98.5\%
\]
Thus, the answer is:
**98.5%**