To balance the scale so there is an equal mass of marbles on each side, what should you do? an unbalanced scale with four marbles on the left side and three marbles on the right side

Add a marble to the right side
Take a marble off the right side
Add two marbles to the right side
Take two marbles from the left side

If the speed of a particle triples ,by what factor does its kinetic energy increase?

Point charges q1 = 51 µc and q2 = −27 µc are placed 1.0 m apart, with q2 on the right. what is the force (in n) on a third charge q3 = 19 µc placed midway between q1 and q2? (assume the positive direction is to the right. indicate the direction with the sign of your answer.)

Two identical stars with mass m orbit around their center of mass. each orbit is circular and has radius r, so that the two stars are always on opposite sides of the circle. (a) find the gravitational force of one star on the other. (b) find the orbital speed of each star and the period of the orbit. (c) how much energy would be required to separate the two stars to infinity?