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torque-direction of rotation

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 ?first part of image here: http://imgur.com/ZNdGrCNsecond part of image here: http://imgur.com/zOWi2Mj
(edited 8 years ago)
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Reply 2
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?
Original post by wilson dang
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?


I'm a bit confused. there is no rotation in the question you linked - it's just about taking moments for a static beam.
Reply 4
Original post by Joinedup
I'm a bit confused. there is no rotation in the question you linked - it's just about taking moments for a static beam.


can you explain how to determine the direction of each force (whether it is clockwise or anticlockwise) ??
Original post by wilson dang
can you explain how to determine the direction of each force (whether it is clockwise or anticlockwise) ??


you take moments about one point at a time.

imagine the point you're taking moments about is the centre of a clock and the point the force is acting on is the end of a clock hand.

decide whether the force is acting on the clock hand in a anti clockwise or clockwise direction.

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