It asks you which of the following is having work DONE on IT. When you lift up the grocery bag, you have work done on the grocery bag. When a crane moves dirt, the crane is having work done on the dirt. and in D, I thought if it really counts, but I believe it does since you push the crate along the floor I guess. I'm sure about A and B, not that sure about D though. Have a noice day!
Bending occurs when one side of the wave enters the new medium before the other side of the wave. ... The bending occurs because the two sides of the wave are traveling at different speeds.
