Recall and use the equation work done = force × distance moved in the direction of the force, W = Fd

Define gravitational field strength as force per unit mass; recall and use the equation gravitational field strength = weight / mass, g = W/m and know that this is equivalent to the acceleration of free fall

Define resultant force as the change in momentum per unit time; recall and use the equation resultant force = change in momentum / time taken, F = Δp/Δt