What nuclear reaction is the energy source of a white dwarf?

a. carbon and helium fusing into oxygen
b. none
c. helium fusing into carbon
d. hydrogen fusing into helium
e. oxygen fusing into silicon

You are driving directly behind a pickup truck, going at the same speed as the truck. a crate falls from the bed of the truck to the road. (a) will your car hit the crate before the crate hits the road if you neither brake nor swerve? (b) during the fall, is the horizontal speed of the crate more than, less than, or the same as that of the truck?