Answer:
from food eaten (i.e contain carnlbohyadrates)
Explanation :
The forces acting on hot- air balloon are:
Weight, (W)
Force due to air resistance, (F)
Upthrust force, (U)
Its weight W is acting in downward direction. The upthrust force U acts in upward direction. When the balloon is moving upward, the air resistance is in downward and vice versa.
In this case, the hot-air balloon descends vertically at constant speed.
so, 
and 
so,
....................(1)
when it is ascending let the weight that it is releasing is R, so
..........(2)
solving equation (1) and (2)

2F is the weight of material that must be released from the balloon so that it ascends vertically at the same constant speed.
A). Convection is heating the soup in the pot.
When you stick the spoon into the hot soup,
conduction heats the spoon all the way up to the end.
b). Water conducts heat a little bit.
But convection is much more responsible for the
uniform distribution of temperature in the kiddie pool.
c). The heat from the metal bench conducts directly
to the buttus epidermis when you sit on it.
d). You feel the heat on your face ... but not on the back of your
neck ... on account of radiation from the fire and the hot grill.