A book with a mass of 1kg is dropped at the height of 0.5m. what is the potential energy of the book when it reaches the bottom? HELLLP also please explain how to get the answer

Identify the type of synthetic material used in each object

Light from a sodium lamp passes through a diffraction grating that has 1000 slits per millimeter. the interference pattern is viewed on a screen 1.000 m behind the grating. the first (m = 1) two bright yellow fringes that are visible are 0.7288 m and 0.7300 m from the central maximum. what are the wavelengths of these two fringes?

Arowboat passenger uses an oar to push the boat off the dock by exerting a force of 40n for 3.0s. what impulse acts on the boat.