How long does it take the ball to fall from roof to the ground 25 feet below

How would doubling the made of an object change the objects potential energy

Astudent is given an assignment to demonstrate diffraction. he takes a photograph of a straw in a glass of water. the straw appears bent at the water level. which best describes this example? a) this is a good example of diffraction. b) this is an example of dispersion and not diffraction. c) this is an example of refraction and not diffraction. d) this is an example of reflection and not diffraction.

When you push downward on a book at rest on a table, you feel an upward force. does this force depend on friction? defend your answer.