Explain why a race car has a displacement of zero if it travels around a 2.5 mile long race track for 10 laps. Why isn't the displacement 25 miles instead?

What are the three ways that an object can accelerate

Consider a system to be two train cars traveling toward each other. what is the total momentum of the system before the train cars collide?   kg • what must the total momentum of the system be after the train cars collide?   kg •  

What is the rate of 12 liters of water moving through a water hose in 4.0 minutes?