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

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SUMMARY

In the discussed scenario, student B (60 kg) cannot lift student A (70 kg) off the ground by pulling on the rope due to the difference in their weights. The gravitational force acting on student A is 700 N, while student B exerts only 600 N. Although student B can create tension in the rope by accelerating upwards, this tension will not exceed the gravitational force acting on student A. Therefore, student A remains grounded unless additional forces are applied.

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  • Understanding of Newton's laws of motion
  • Basic knowledge of gravitational force calculations
  • Familiarity with tension in ropes and pulleys
  • Concept of normal force in physics
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This discussion is beneficial for physics students, educators, and anyone interested in understanding the mechanics of forces, tension, and pulleys in real-world applications.

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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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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?
 
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.
 

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