Fine grains of beach sand are assumed to be
spheres of radius 38.9 µm. these grains are
made of silicon dioxide which has a density of
2600 kg/m3
.
what is the mass of each grain of sand?
answer in units of kg.

Gam radio signals can usually be heard behind a hill, but fm often cannot. that is, am signals bend more than fm. explain. (radio signals, as we shall see, are carried by electromagnetic waves whose wavelength for am is typically 200 to 600 m and for fm about 3 m.)

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?

Power can be defined as a. the distance over which work was done. b. how much work can be done in a given time. c. all the work in an given area. d. the energy required to do work.