As thermal energy is added to a sample of water, the kinetic energy of its molecules increases, but the particles remain close together. Which part of
the heating curve illustrates this process?

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?