High School Physics : Understanding Torque
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Example Questions
Example Question #331 : Motion And Mechanics
A child spins a top with a radius of 
Torque is a force times the radius of the circle, given by the formula:
In this case, we are given the radius in centimeters, so be sure to convert to meters:
Use this radius and the given force to solve for the torque.
Example Question #1 : Understanding Torque
Two children are trying to balance on a 
If the see-saw is 
The question is asking us to find the equilibrium point; that means we want the net torque to equal zero.
Now, find the torque for the first child.
We are going to use the force of gravity for the force of the child.
When thinking of torque, treat the positive/negative as being clockwise vs. counter-clockwise instead of up vs. down. In this case, child one is generating counter-clockwise torque. That means that since 
Solve for the radius (distance) of the second child.
Example Question #3 : Understanding Torque
A 
The formula for torque is:
In this formula, 
Example Question #61 : Circular Motion
In ancient Greece, construction workers would use long levers to lift up boulders. Assume a boulder has a mass of 
We know that the system will be in equilibrium at the final point, meaning that the final net torque must be zero. That means that the torque generated by the boulder and the torque generated by the construction worker should be equal.
The negative sign is due to the placement of the two masses on opposite sides of the fulcrum. Essentially, one mass will have a positive radius and the other will have a negative radius. Use the definition of torque to expand this equation.
In this case, the forces will be the weights of the two objects due to gravity.
We can cancel the acceleration due to gravity from the equation to simplify.
Using the given information from the question, we can solve for the distance between the worker and the fulcrum. We know the mass of the worker, the mass of the boulder, and the distance between the boulder and the fulcrum.
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