Why friction made it difficult to discover newton’s first law of motion.

Which type of wave can travel without a medium

What are similarities and differences between refraction, reflection, diffraction and absorption?

Two carts, one of mass 2m and one of mass m, approach each other with the same speed, v. when the carts collide, they hook together. assume that positive momentum is to the right. which graph best represents the momentum of both carts over time, before and after the collision?