Final answer:
A car with a mass of 900 kg and a truck with a mass of 1800 kg would have the same momentum if the car travels at twice the velocity of the truck. This is consistent with the momentum equation and the law of conservation of momentum.
Step-by-step explanation:
To determine when a car with a mass of 900 kg and a truck with a mass of 1800 kg would have the same momentum, we need to understand the relationship between mass and velocity in the momentum equation. The momentum of an object is calculated by multiplying its mass by its velocity (momentum = mass × velocity). Therefore, for the car and truck to have the same momentum, the car must be traveling at twice the velocity of the truck, as its mass is half that of the truck.
For example, if the truck is moving at a velocity of 20 m/s, the car must move at 40 m/s in order to have the same momentum. This is because when we calculate their momenta, they would both have a momentum of 1800 kg × 20 m/s for the truck, and 900 kg × 40 m/s for the car, both resulting in 36,000 kg⋅m/s. The conservation of momentum principle in physics states that if no external forces are acting on a system, its total momentum remains constant.