The answer is C. If the box is accelerating, that means that the amount of force you are exerting is greater than the force of the box.
At stp (standard temperature and pressure), the temperature is T=0 C=273 K and the pressure is p=1.00 atm. So we can use the ideal gas law to find the number of moles of helium:

where p is the pressure (1.00 atm), V the volume (20.0 L), n the number of moles, T the temperature (273 K) and

the gas constant. Using the numbers and re-arranging the formula, we can calculate n:
Explanation:
use equation power=watts/time
to find time rearrange to make time = power/wats
so you have your equation substitute the numbers
so 9560J/860W is 11 minutes
In a direct current, the electric charge, or current, only flows in one direction. In an alternating current, the electric charge changes periodically.
I found the answer for you if u need any help ask anytime!