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:no it is staying the same speed
Explanation:
Answer:
They're going to increase the total resistance as 
Explanation:
If the resistors are in parallel, the potential difference is the same for each resistor. But the total current is the sum of the currents that pass through each of the resistors. Then

where

but
for 
so

where

Answer:
Explanation:
Given
initial velocity component of engines is


time period of engine running=763 s
Displacement in 

Using
in x and y direction




In y direction




x component
y component