Relating Pendulum SHM

ehabmozart

I've seen in many sites that a pendulum restoring force Fnet = mg sin theta... Why did we actually get the vector direction of the weight and not the vector of the tension.. Simply, as in centrepetal force.. It would be Tsin theta would be the net restoring force??? Thanks!

nasu

The restoring force is the net force acting on the pendulum's bob.
If you add the tension and the weight (as vectors) and consider inextensible suspension string the resultant is tangent to the trajectory and its magnitude is mg sinθ.

ehabmozart

Can i have illustrations then??

nasu

Sure you can. Draw the forces acting on the pendulum and then take the components along the tangential and radial directions.

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ehabmozart	Relating Pendulum SHM I've seen in many sites that a pendulum restoring force Fnet = mg sin theta... Why did we actually get the vector direction of the weight and not the vector of the tension.. Simply, as in centrepetal force.. It would be Tsin theta would be the net restoring force??? Thanks!

nasu	The restoring force is the net force acting on the pendulum's bob. If you add the tension and the weight (as vectors) and consider inextensible suspension string the resultant is tangent to the trajectory and its magnitude is mg sinθ.

nasu	Relating Pendulum SHM Sure you can. Draw the forces acting on the pendulum and then take the components along the tangential and radial directions.