A simple pendulum length 'L' with bob of mass 'm' is slightly displaced from its mean position so that it string makes an angle 'θ' with vertical line as shown in the figure. Then bob of pendulum released. What will be the expression of torque with which the bob starts to move towards the mean position?
Correct answer: B. mgL sin θ
- A. mgL
- B. mgL sin θ
- C. 0
- D. mgL cos θ
Explanation
Torque is the rate of change of angular momentum of an object T=force*radius*sinθ, in this case, force is the weight of the pendulum (mg) and radius is the length of the string.
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About Angular Displacement
Angular displacement measures the change in a body’s angular position and is expressed in radians or degrees, with anticlockwise and clockwise directions assigned signs. It connects to arc length, angular velocity and angular acceleration, and must be distinguished from ordinary linear displacement in rotational motion.
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