What causes the phases of the moon as seen from earth?
a. light from the sun reflects off the moon as it orbits earth.
b. hundreds of thousands of miles lie between the moon and earth.
c. earth’s shadow projects onto the moon.
d. earth spins on its axis relative to the moon.
e. earth has an atmosphere, and the moon doesn’t.?

a. light from the sun reflects off the moon as it orbits earth.  

Explanation:

Moon does not have its own light, it reflects the sunlight falling on it. Phases of moon are the different shapes of the moon that we see. There are mainly 5 phases of moon: New moon, Crescent, Half moon, gibbous and full moon. These shapes are due to the illuminated portion of the moon (by the Sun) that is visible from the Earth.

Thus, option a is correct.

two charges are fixed in place on the x-axis as shown. the charge at x = 0 is negative and has magnitude q = 2 μcoulombs (1 μcoulomb = 10-6 coulombs). the charge at x = d, (d = +12 cm), is positive and has magnitude q = 4 μcoulombs. find a point x = xo along the x-axis at which the electric field is zero.

0.93xc=0.93x3x10^8m/s

2.54cm is 1 inch

360seconds i 1 hr