Jacob is helping store bales of hay on his uncle's farm. The bales weigh 50 pounds and he has to lift them up over his head to stack them. His maximum lift is 55 pounds. He finds some rusty pulleys that he can attach about 20 feet off the ground. Which of the following is/are important when determining if the pulleys will help him get his job done (choose all that apply).

Question

(2 points)
Responses

He knows it takes most of his energy to lift a bale, so he needs the pulleys to have high efficiency so they convert almost all his energy into lifting the bale as he pulls the rope.
He knows it takes most of his energy to lift a bale, so he needs the pulleys to have high efficiency so they convert almost all his energy into lifting the bale as he pulls the rope.

He needs the wheels to be at least 12" across since the bales are 120" in size.
He needs the wheels to be at least 12" across since the bales are 120" in size.

He has to consider the weight of the metal pulleys to calculate the efficiency
He has to consider the weight of the metal pulleys to calculate the efficiency

He has to consider whether the rust has increased the friction so much that the efficiency has been severely reduced.

Answer 1

When determining if the pulleys will help Jacob get his job done, the following responses are important:

1. He knows it takes most of his energy to lift a bale, so he needs the pulleys to have high efficiency so they convert almost all his energy into lifting the bale as he pulls the rope.

2. He has to consider whether the rust has increased the friction so much that the efficiency has been severely reduced.

These two factors are crucial because they relate directly to the efficiency of the pulleys and whether they will effectively assist Jacob in lifting bales of hay. The other options regarding the size of the wheels and considering the weight of the pulleys are not directly relevant to the primary concern of efficiently lifting the bales.