Question

Two identical metal balls are suspended by insulating threads. Both balls have the same net charge. In this problem, do not assume the balls are point charges. a. Draw a separate free-body diagram for each ball. Label the forces to indicate: - the object exerting the force, - the object on which the force is exerted, - the type of force (gravitational, normal, etc.), and - whether the force is a contact or a noncontact force. b. Suppose the charge on the second ball is reduced slightly, so that it is less than that on the first ball. Predict whether the angle that ball l makes with the vertical will be greater than, less than, or equal to the angle that ball 2 makes with the vertical. Explain. Sketch your answer above. Name Ball I Ball 2 Free-body diagram Free-body diagram for ball I for ball 2 - - Ball I Ball 2 How does the free-body diagram for each ball in this case compare to the corresponding freebody diagram that you drew in part a

Answer 1

Here in first case both balls will exert electrostatic force on each other

due to this electrostatic force the two balls will repel each other

Apart from this there will be gravitational force on the two balls which is vertically downwards

Now here we know that as the electrostatic force of repulsion will increase between two balls then the angle between the two balls will be more as the horizontal force will separate the two balls

Part b)

As we decrease the charge on one ball then the net electrostatic force between two balls will decrease as we know that this force will depends on the product of two charges

so here the angle between the two balls will decrease and the two balls will come closer.

Also by the free body diagram of two balls we can see that all the forces on the balls are same so the angle made by the ball with the vertical is same for both the balls

so here the angle that ball l makes with the vertical will be equal to the angle that ball 2 makes with the vertical.