Torque: Why does tension = Friction

In summary, the tension in the horizontal string attached to a 10.0 kg sphere on an incline can be found by using the equations of sum of all horizontal forces and sum of all vertical forces. By taking moments about a point where only the tension and the unknown force have a moment, the relationship between F and T can be determined. This is because the other forces present do not have a moment about that point.
  • #1
anirzehc
3
0

Homework Statement


A 10.0 kg sphere is attached to the incline by a horizontal string. Whats the tension in the string.
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Homework Equations


sum of all horizontal forces = 0
sum of all vertical forces = 0
sum of all torques = 0

The Attempt at a Solution


The sum of the horizontal forces[/B] is -Tsin55 degrees - F + mgsin35 degrees = 0
Why does F= T?
I know F= T because when I substitute F=T and solve for T I get the right answer (30 .9 N) but why is this?
 
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  • #2
anirzehc said:
I know F= T because when I substitute F=T and solve for T I get the right answer (30 .9 N) but why is this?
If you want a quick way to get a relationship between F and T, the trick is to take moments about a point where only those two forces have a moment. What other forces are present? What point do none of those have a moment about?
 

FAQ: Torque: Why does tension = Friction

1. What is torque and how is it related to tension and friction?

Torque is a measure of the rotational force or moment applied to an object. Tension and friction are two types of forces that can create torque. Tension is a pulling or stretching force, while friction is a force that opposes motion or sliding between two surfaces.

2. Why does tension equal friction in the context of torque?

In the context of torque, tension and friction are equal because they are both acting at the same distance from the axis of rotation. This means that they have the same lever arm, or distance, which is a key factor in determining the amount of torque produced. Therefore, tension and friction have equal and opposite effects on the rotational motion of an object, resulting in a net torque of zero.

3. How does the direction of tension and friction affect torque?

The direction of tension and friction affects torque because they are both vector quantities, meaning they have both magnitude and direction. The direction of these forces determines the direction of the torque they produce. If the tension and friction are in opposite directions, they will cancel each other out and result in zero torque. If they are in the same direction, they will add together and produce a net torque in that direction.

4. Can tension and friction both produce a torque on an object?

Yes, both tension and friction can produce torque on an object. As mentioned before, they are both forces that act at a distance from the axis of rotation, which is a key factor in determining torque. However, if the tension and friction are equal in magnitude and acting in opposite directions, they will cancel each other out and not produce a net torque on the object.

5. How does the magnitude of tension and friction affect the torque produced?

The magnitude of tension and friction have a direct relationship with the torque produced. The greater the magnitude of these forces, the greater the torque they will produce. This is because torque is directly proportional to both the magnitude of the force and the length of the lever arm. Therefore, if the tension or friction is increased, the torque produced will also increase.

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