What is the difference between EMS waves and mechanical waves? Select all that apply. * Mechanical wave require a medium to travel on. EMS waves do NOT require a medium to travel on. EMS waves do NOT require a medium to travel on but, they can use a medium to travel on.

When a book falls from a shelf to the ground without anyone pushing on it, no work is done on the book. true or false

An engineer designs a roller coaster so that a car travels horizontally for 152 ft, then climbs 137 ft at an angle of 34.0° above the horizontal. it then moves 137 ft at an angle of 48.0° below the horizontal. if we take the initial horizontal motion of the car to be along the +x-axis, what is the car's displacement? (give the magnitude of your answer, in ft, to at least four significant figures and give the direction of your answer in degrees counterclockwise from the +x-axis.)

The speed of light in a material is 0.50 c. what is the critical angle of a light ray at the interface between the material and a vacuum?