Can a person hanging from a rope pull the person holding the rope up?

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In summary: This increase in tension will cause A's weight to be supported by the rope more than it would be if B wasn't accelerating. In summary, this would allow B to lift A off of the ground.
  • #1
patriots51
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Homework Statement



A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling. One end is held by student A (70 kg) who is at rest. The other side has student b (60 kg).

I need to explain why or why not student b can lift student a off of the ground if he accelerates up the rope, increasing tension.

Homework Equations



the force of student A is 700 N (70kg x 10 m/s^2)
the force of student B is 600 N (60kg x 10m/s^2)
the normal force exerted on student A by the floor is 100N (?)
the force of tension will vary depending on student B's acceleration (F=ma)

The Attempt at a Solution



I don't believe that it would be possible to pull the person holding the rope up, but I'm not sure how to prove it.
 
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  • #2
patriots51 said:

Homework Statement



A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling. One end is held by student A (70 kg) who is at rest. The other side has student b (60 kg).

I need to explain why or why not student b can lift student a off of the ground if he accelerates up the rope, increasing tension.

Homework Equations



the force of student A is 700 N (70kg x 10 m/s^2)
the force of student B is 600 N (60kg x 10m/s^2)
the normal force exerted on student A by the floor is 100N (?)
the force of tension will vary depending on student B's acceleration (F=ma)



The Attempt at a Solution



I don't believe that it would be possible to pull the person holding the rope up, but I'm not sure how to prove it.
Hello patriots51. Welcome to PF !

If you were told that it is possible for student B to lift student A off of the ground, could you explain how it's possible?
 
  • #3
patriots51 said:
A rope of negligible mass passes over a pulley of negligible mass attached to the ceiling. One end is held by student A (70 kg) who is at rest. The other side has student b (60 kg).

I need to explain why or why not student b can lift student a off of the ground if he accelerates up the rope, increasing tension.
To demonstrate "lifting off the ground" B just needs to momentarily cause A's feet leave the floor.
 

1. Can a person hanging from a rope pull the person holding the rope up?

No, a person hanging from a rope cannot pull the person holding the rope up. This is because the person hanging from the rope is not in a position to exert force on the person holding the rope, and the person holding the rope would need to be significantly stronger than the person hanging in order to lift them up.

2. Why is it physically impossible for a person hanging from a rope to pull the person holding the rope up?

It is physically impossible for a person hanging from a rope to pull the person holding the rope up because of the laws of physics. In order for an object to exert force on another object, it must have a solid surface to push against. When a person is hanging from a rope, they do not have a solid surface to push against, making it impossible for them to exert force on the person holding the rope.

3. Could the person holding the rope use a pulley system to lift the person hanging from the rope?

Yes, the person holding the rope could use a pulley system to lift the person hanging from the rope. A pulley system allows for the distribution of weight, making it easier for the person holding the rope to lift the weight of the person hanging. However, the person holding the rope would still need to be significantly stronger in order to lift the person hanging.

4. Is it possible for two people to lift each other up while hanging from a rope?

No, it is not possible for two people to lift each other up while hanging from a rope. This is because both people would need a solid surface to push against in order to exert force on each other. Since they are both hanging from the same rope, they do not have a solid surface to push against, making it impossible for them to lift each other up.

5. What factors would affect the likelihood of a person hanging from a rope being able to pull the person holding the rope up?

The likelihood of a person hanging from a rope being able to pull the person holding the rope up would depend on several factors, such as the weight and strength of the person hanging, the weight and strength of the person holding the rope, and the type and quality of the rope and any equipment being used. Generally, it is highly unlikely that a person hanging from a rope would be able to pull the person holding the rope up, regardless of these factors.

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