According to the universal law of gravity, everything has a gravitational force.
a. true
b. false

Which material produces static charge when rubbed?

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?

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?