I believe the answer for 1) is
PEgrav = mass • g • height
PEgrav = m *• g • h
When you work out it helps clear your thoughts and think of nothing. It makes you feel good.
The sunlight of all colors passes through air, the blue part causes charged particles to oscillate faster than does the red part. More of the sunlight entering the atmosphere is blue than violet, however, and our eyes are somewhat more sensitive to blue light than to violet light, so the sky appears blue.
