If you're falling in a forest and there's nobody around, do you ever really crash, or even make a sound?

In what direction does the medium move relative to the direction of the wave? explain.

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?

Acamcorder has a power rating of 20 watts. if the output voltage from its battery is 9 volts, what current does it use?