How Does Force Direction Affect Rotation in Physics Problems?

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In summary, when determining the direction of rotation, it is important to consider the direction of the force and the point of application relative to the chosen reference point. One can use a thumb rule to figure it out, but it is generally easy to understand by simply thinking about the direction in which the force would cause the object to rotate.
  • #1
goldfish9776
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Homework Statement


Taking moment about A , the mass of 2.0g and 0.50g is rotated in the clockwise direction is because they are both directed in downwards position ? while R2 is acted in upward direction , so it is rotated in counter clockwise direction ?

Taking moment about G , why R1 is rotated in the clockwise direction ? while 2.0g and R2 is rotated in anticlockwise direction ?

How to determine the direction of rotation ?

Homework Equations

The Attempt at a Solution

 

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  • #2
goldfish9776 said:

Homework Statement


Taking moment about A , the mass of 2.0g and 0.50g is rotated in the clockwise direction is because they are both directed in downwards position ? while R2 is acted in upward direction , so it is rotated in counter clockwise direction ?

Taking moment about G , why R1 is rotated in the clockwise direction ? while 2.0g and R2 is rotated in anticlockwise direction ?

How to determine the direction of rotation ?

It depends 1.) on the direction of the force and 2.) the point of application of the force relative to the reference point about which the moments are taken.

Compare the direction of the moment of a force taken about A to the direction of the moment for the same force taken about G.

If it helps, imagine a see-saw.
 
  • #3
SteamKing said:
n of the force and 2.) the point of
SteamKing said:
It depends 1.) on the direction of the force and 2.) the point of application of the force relative to the reference point about which the moments are taken.

Compare the direction of the moment of a force taken about A to the direction of the moment for the same force taken about G.

If it helps, imagine a see-saw.
For taking moment about G , I tried determine the direction of rotation using the thumb rule , I found the ans is correct . For the forces on the left G , I use LEFT HAND THUMB RULE , I found it should rotate in clockwise because of the R1 acted in upwards direction .

My question is can I determine the direction of rotation in this way ? is LEFT HAND THUMB RULE exist in physics?
 
  • #4
goldfish9776 said:
For taking moment about G , I tried determine the direction of rotation using the thumb rule , I found the ans is correct . For the forces on the left G , I use LEFT HAND THUMB RULE , I found it should rotate in clockwise because of the R1 acted in upwards direction .

My question is can I determine the direction of rotation in this way ? is LEFT HAND THUMB RULE exist in physics?
You can certainly use a thumb rule to figure it out, though I don't understand why you need it here. Isn't it obvious which way each force tends to turn about the chosen axis?
Whether it's LH or RH rule depends on how you assign your fingers to the different vectors.
 
  • #5
haruspex said:
You can certainly use a thumb rule to figure it out, though I don't understand why you need it here. Isn't it obvious which way each force tends to turn about the chosen axis?
Whether it's LH or RH rule depends on how you assign your fingers to the different vectors.
Why you said it is obvious to figure out the force turn about the chosen axis ? I have problem of finding out the direction of the force...Can you give me an example and explain on it ?
 
  • #6
goldfish9776 said:
Why you said it is obvious to figure out the force turn about the chosen axis ? I have problem of finding out the direction of the force...Can you give me an example and explain on it ?
The force points in the direction of the arrow head in the diagram. That's how vectors like forces are generally represented graphically.
 
  • #7
goldfish9776 said:
Why you said it is obvious to figure out the force turn about the chosen axis ? I have problem of finding out the direction of the force...Can you give me an example and explain on it ?
Take this example:
goldfish9776 said:
Taking moment about G , why R1 is rotated in the clockwise direction ?
Consider G as a pivot. R1 is an upward force at A, to the left of the pivot. Ignore all other forces for the moment. If you were to push up on the rod at A, which way would you expect the rod to turn?
 
  • #8
haruspex said:
Take this example:

Consider G as a pivot. R1 is an upward force at A, to the left of the pivot. Ignore all other forces for the moment. If you were to push up on the rod at A, which way would you expect the rod to turn?
clockwise . Lol , the principle is easy to understand , why didn't I think of this ? *facepalm*
 

FAQ: How Does Force Direction Affect Rotation in Physics Problems?

1. What is torque-direction of rotation?

Torque-direction of rotation refers to the direction in which an object will rotate when a torque, or force that causes rotation, is applied to it. The direction of rotation is determined by the direction of the torque vector.

2. How is torque-direction of rotation measured?

Torque-direction of rotation is typically measured using a torque wrench or other torque measuring device. The direction is indicated by the direction of the torque vector, which can be clockwise or counterclockwise.

3. How does torque-direction of rotation affect the movement of an object?

The direction of torque determines the direction of rotation, so it plays a crucial role in the movement of an object. If the torque-direction is in the same direction as the object's moment of inertia, the object will rotate in that direction. If the torque-direction is opposite to the moment of inertia, the object will rotate in the opposite direction.

4. Can torque-direction of rotation be changed?

Yes, torque-direction of rotation can be changed by altering the direction of the torque vector. This can be done by changing the direction of the force applied, or by changing the position of the force relative to the object's center of rotation.

5. Why is understanding torque-direction of rotation important in science?

Understanding torque-direction of rotation is important in science because it helps us understand and predict the movement of objects. This knowledge is crucial in fields such as mechanics, engineering, and physics, where precise control and manipulation of rotational movement is necessary.

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