How much heat is needed to vaporize 100 g of water at 100 degrees C? a. 54,000 cal
b. 100 cal
c. 80 cal
d. 800 cal

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.

How is the gravitational force related to the distance between two objects?

Need only answer if you think you know it