a real car is moving at 10 km/h has more momentum than a toy car moving at the same rate because??

Momentum is P=mass*velocity Be that it may the real car and toy car travel at the same velocity, the real car has a much larger mass. Since Momentum is directly proportional to mass, the real cars momentum is therefore larger.

The amount of kinetic energy that is transferred from movement is the same but the mass is different. Which means there is more to stop or rather more energy transferred into the object with larger mass.