Two carts move in the same direction along a frictionless air track, each acted on by the same constant force for a time interval Δt. Cart 2 has twice the mass of cart 1. Which one of the following statements is true? (a) Each cart has the same change in momentum. (b) Cart 1 has the greater change in momentum. (c) Cart 2 has the greater change in momentum. (d) The changes in momenta depend on the initial velocities.