Discover the Force Needed for a Man to Rise on a Bosun Chair | Mass=95Kg

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In summary, a small man weighing 95kg is sitting in a bosun chair attached to a massless rope and pulley system. To rise, the man must pull on the rope with a force of at least 465.5N, which is equivalent to half the weight of the man and chair combined. Any force greater than 465.5N will cause the man and chair to accelerate upwards. The man can also use his feet on the ground to push himself up, but he must maintain a constant force of 465.5N on the rope to rise at a constant speed. There are three unknowns in the system, making it necessary to draw multiple free body diagrams to accurately solve the problem.
  • #1
suspenc3
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A small man is sitting in a bosun chair that dangles from a massless rope, which runs over a massless frictionless pulley and back down to the mans hand. The combined mass of the man and the chair is 95kg. with what force magnitude must the man pull on the rope if he is to rise?

Mass = 95Kg
a = ?
v = ?
F = ?

I didnt get very far with this one, I drew one F.B.D for the man and got the following:
Nothing in the X direction
y--------T+v = -mg

Heres a link to a drawing
http://img438.imageshack.us/img438/8349/pulley27xt.png

Should i draw another F.B.D for the mans hands on the rope?
 
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  • #2
if so would T act up onlong with mg and v act downwards?
 
  • #3
Hi, the weigh of the man + weigh of the chair is around 950 N.
When the man pulls hiomself with his hand with a force F, the chair exerts also a force F on him.
Just to have equilibrium 2F = 950 N so F = 450 N
With a little push up (say with his feet on the ground) the chair and him will move up at a constant speed if he maintains the constant force 450 N on the rope
Any force greather than 450 N will cause an acceleration of the man and the chair up in the air.
I hope it helps you
 
  • #4
so there's no math involved?
kinda makes sense since there are 3 unknows..

2f = 931N
f = 465.5N

Also there is more to the question..si are my free body diagrams correct?
 
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Related to Discover the Force Needed for a Man to Rise on a Bosun Chair | Mass=95Kg

1. What is a pulley?

A pulley is a simple machine that consists of a wheel with a groove around its circumference, and a rope or cable that runs through the groove. It is used to change the direction of a force, making it easier to lift or move heavy objects.

2. How does a pulley work?

A pulley works by distributing the weight of an object over multiple ropes, which reduces the amount of force needed to lift the object. The more ropes that are used, the less force is required. This is known as mechanical advantage.

3. What are the different types of pulleys?

There are three main types of pulleys: fixed, movable, and compound. Fixed pulleys are attached to a stationary object and change the direction of the force. Movable pulleys are attached to the object being lifted and move with it. Compound pulleys combine fixed and movable pulleys to increase the mechanical advantage.

4. How do I calculate the mechanical advantage of a pulley system?

The mechanical advantage of a pulley system is determined by counting the number of ropes supporting the object being lifted. For example, if a system has 3 ropes supporting the object, the mechanical advantage is 3. You can also calculate it by dividing the output force by the input force.

5. What are some real-life examples of pulleys?

Pulleys are used in many everyday objects and systems. Some common examples include elevators, cranes, flagpoles, and exercise machines. They are also used in industrial and construction settings to lift heavy materials and equipment.

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