How far apart should two protons be if the electrical force of repulsion on each one is equal to its weight on the earth? ( k = 1/4πε 0 = 9.0 × 10 9 N ∙ m 2/C 2, e = 1.6 × 10^ -19 C, m proton = 1.67 × 10^ -27 kg)

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?

Which of the following is the phase that results when the moon is on the opposite side of the earth from the sun? a. quarter moon b. crescent moon c. new moon d. full moon

Aplayground merry-go-round has a radius of 4.6 m and a moment of inertia of 200 kg-m2 and turns with negligible friction about a vertical axle through its center. a child applies a 26.0 n force tangentially to the edge of the merry-go-round for 15.0 seconds. if the merry-go-round is initially at rest, how much work did the child do on the merry-go-round?