What is the equation for calculating the electrical force, F3, between two charges

Name three different units of energy used to measure heat and describe what type of situations each is usually used.

Which type of wave can travel without a medium

Under the action of a constant force an object accelerates at 7.8 m/s2. what will the acceleration be if (a) the force is halved? (b) the object's mass is halved? (c) the force and the object's mass are both halved? (d) the force is halved and the object's mass is doubled?