A runaway train that has a mass of 67,177 kg and is travelling at a speed of 59 m/s. How much work does Superman do in slowing the train down to a controllable speed of 11 m/s?

How is the gravitational force related to the distance between two objects?

What changes occur in the brain during the teenage years? 25 points, someone me out!a.) thinking becomes slower as the brain grows larger. b.) connections between neurons become stronger and faster. c.) unused neurons fuse together to form larger, better functioning neurons. d.) more neurons are developed.

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 •