Asmall but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. the other end of the rod is attached to a frictionless pivot. the rod is raised until it is vertical, with the stone above the pivot. the rod is released and the stone moves in a vertical circle with no air resistance. what is the tension in the rod as the stone moves through the bottom of the circle? (a) 20 n (b) 40 n (c) 60 n (d) 80 n (e) 100 n

Option B is the correct answer.

Explanation:

Refer the figure we have centripetal force at bottom of circle

       

We have mass, m = 2 kg

Radius, r = 1.2 m

For circular motion to occur we have tension at top = 0

That is

       

Now let us find tension at bottom point

       

Option B is the correct answer.  

         

Efficiency is an action of doing something. for example when you take a test. good efficiency means you did well but bad effeciency or no effiency means you did bad.

Is a  vector quantity  that refers to "the rate at which an object changes its position." imagine a person moving rapidly - one step forward and one step back - always returning to the original starting position. while this might result in a frenzy of activity, it would result in a zero velocity. because the person always returns to the original position, the motion would never result in a change in position. since velocity is defined as the rate at which the position changes, this motion results in zero velocity. if a person in motion wishes to maximize their velocity, then that person must make every effort to maximize the amount that they are displaced from their original position. every step must go into moving that person further from where he or she started. for certain, the person should never change directions and begin to return to the starting position.