| Two companion lenses made of the same material have the focal length of the first lens (100 cm) placed on one axis at a certain distance so that the ocular lens has a focal length of (50 cm). Find the focal length of the second lens and the distance between the two lenses?

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 •  

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?

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?