What is the gravitational potential energy of a 150 kg object suspended 5m above the earth's surface

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Which governments provide garbage collection services to homes and businesses

How much work would it take to move a coulomb charge across a 4 volt potential difference?