# Torque Problems

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```					                                    Torque Problems

1. A 3 foot wide door requires a 20 lb force to open it.
a) What is the torque on the door?
b) Assuming that you need the same torque to open the door, what force would be
required if the person pushes at the middle of the door?
c) Assuming that you need the same torque to open the door, what force would be
required if the person pushes 6 in from the hinge?

2. Two children sit on a see-saw. The see-saw is 16 feet long from end to end. One
child weighs 50 lb and sits at the very end of the see-saw. The other child weighs
75 lb. Where should the 75 pound child sit so that the see-saw is balanced?

3. A motorist has a flat tire on the highway. He has to jack up the car to change the tire,
but finds no jack in the trunk. He finds a 15 ft long log on the side of the road. He
places the log on a stone that acts as a pivot point. The 2000 lb car is placed 1 ft
from the pivot point. If the motorist can only push with a force of 200 lb, how far
from the pivot point must he push to raise the car?

4. Two children sit on a see-saw as shown in the diagram below.

Child #2

Child #1

Child #1 weighs 45 lb and sits 3 ft from the pivot point. Child #2 weighs 35 lb and
sits 4 ft from the pivot point. Will the seesaw rotate counterclockwise, clockwise or
stand still? Be sure to show all your work in order to prove your answer.

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 views: 11 posted: 10/31/2010 language: English pages: 1