Why are some electromagnetic waves harmful to you but others are not?

Which example has gravitational potential energy? a.a horse slowing down from a run b.an apple about to fall from a tree branch c.a bicycle being pedaled down a horizontal path d.beaker sitting on the floor

All the simple machines make work easier to do by changing the or of a force. a. size; type b. work; type c. size; direction d. type; direction

Alfred pushes on a heavy box, but cannot move it. the box has a lot of inertia motion friction gravity