# Physics

A boy sits in a tire that is attached to a rope that passes over a pulley fastened to the ceiling and then passes back down to the boy's hands. The weight of the boy plus the tire is W. The force with which the boy must pull on the free end of the rope to support his weight in the tire is:

(a) (1/2)W
(b) W
(c) 2W
(d) (2/3)W
(e) (3/2)W

1. 👍
2. 👎
3. 👁
1. Well, downward forces are W, and upward forces are his Pull, and tension.

So his pull + Tension=W on the tire side.
On the other side, tension=Pulling force
so
Pull+tension=W
Pull+ Pull=W
do the math.

1. 👍
2. 👎
👤
bobpursley
2. Ok, I think I got it. Are these free body diagrams correct? (ignore the dots)

TIRE+BOY:

T F
|.|
.|
W

FREE END:

.T
.|
.|
.F

SYSTEM:

.F
.|
.|
.T.....(This tension is down)
T.F....(This tension is up)
|.|
.|
.W

CANCELING TENSIONS:

2F
|
|
W

2F=W so F=(1/2)W

1. 👍
2. 👎
3. Now I'm confused. Why does changing the direction of a force double it? I'm also confused about whether the tension is a reaction to the weight of the tire and the boy or the force that the boy pulls down on the rope with. Also if the force in the free body diagram of the system were another person pulling the tire and the boy up, why would the force not be half the weight in that case?

1. 👍
2. 👎

## Similar Questions

1. ### physics

What is the tension in the rope of this figure description? 60 kg person is hanging in the air on a rope attached to a pulley, with a 100 kg mass attached on other end that is touching the ground.

2. ### physics

A gymnast of mass 61.0 kg hangs from a vertical rope attached to the ceiling. You can ignore the weight of the rope and assume that the rope does not stretch. How do I calculate the tension T in the rope if the gymnast hangs

3. ### Calculas

A boat is pulled into a dock by means of a rope attached to a pulley on the dock. The rope is attached to the bow of the boat at a point 10 ft below the pulley. If the rope is pulled through the pulley at a rate of 20 ft/min, at

4. ### kjkj

A gymnast of mass 56.0kg hangs from a vertical rope attached to the ceiling. You can ignore the weight of the rope and assume that the rope does not stretch. Use the value 9.81m/s2 for the acceleration of gravity.Calculate the

1. ### physics

A boy pulls a sled of mass 5.0 kg with a rope that makes an 60.0° angle with respect to the horizontal surface of a frozen pond. The boy pulls on the rope with a force of 10.0 N; and the sled moves with constant velocity. What is

2. ### Phyics

A spiral staircase winds up to the top of a tower in an old castle. To measure the height of the tower, a rope is attached to the top of the tower and hung down the center of the staircase. However, nothing is available with which

3. ### physics

A gymnast of mass 63.0 {\rm kg} hangs from a vertical rope attached to the ceiling. You can ignore the weight of the rope and assume that the rope does not stretch.Calculate the tension T in the rope if the gymnast climbs up the

4. ### physics

a boy of mass 40kg and a girl of 30kg play on a see saw of negligible weight.if the boy sits 270cm from the pivot of the see-saw where must the girl sit to make it balance

1. ### physic

A block with mass m1 hangs from a rope that is extended over an ideal pulley and attached to a second block with mass m2 that sits on a ledge. The second block is also connected to a third block with mass m3 by a second rope that

2. ### Physics

A 2kg mass is suspended on a rope that wraps around a frictionless pulley attached to the ceiling with a mass of 0.01kg and a radius of 0.25m. The other end of the rope is attached to a massless suspended platform, upon which

3. ### Physics

When the three blocks in the figure below are released from rest, they accelerate with a magnitude of 0.370 m/s2. Block 1 has mass M, block 2 has 5M, and block 3 has 5M. What is the coefficient of kinetic friction between block 2

4. ### Physics (Trig Bit)

A boy and a girl carry a 12.0 kg bucket of water by holding the ends of a rope with the bucket attached at the middle. FI tehre is an angle of 100.0 degrees between the two segments of the rope, what is the tension in each part? I