A loaded truck and an empty truck of the same type are moving at the same speed. Which truck is easier to stop by braking?
Answer: It is easy to stop an empty truck by applying the brakes. Even though both trucks are moving at the same speed and the trucks are exactly the same, the freight truck has more momentum than the empty truck because the freight truck has more mass.
Because the momentum of the truck = mass of truck × velocity of truck. Since the freight truck has more momentum, it needs more braking force to stop it, so the empty truck will be easier to stop.