Which equation is correct???

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 •  

Which magnetic property best describes a magnet’s ability to act at a distance? magnets are dipolar. magnets attract only certain objects. magnets have magnetic fields. magnets can transfer their properties to certain materials.

Astudent pushes a 60-n block across the floor for a distance of 10 m. how much work was done to move the block