Answer:
Option D
Explanation:
The work done can be given by the mechanical energy used to do work, i.e., Kinetic energy and potential energy provided to do the work.
In all the cases, except option D, the energy provided to do the useful work is not zero and hence work done is not zero.
In option D, the box is being pulled with constant velocity, making the acceleration zero and thus Kinetic energy of the system is zero. Hence work done in this case is zero.
Answer:
The time it can operate between chargins in minutes is

Explanation:
Given:
,
, 
a). The rotational kinetic energy






b). The power average 0.8kW un range time can be find

Solve to t'



The answer is D I’m not really sure yet
For the first hour, the slope is zero.
After that, the slope is -2 miles per hour.