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: True
A water pump
belong to a positive displacement pump that provides constant flow of water at
fixed speed, regardless of changes in the counter pressure. The two main types
of positive displacement pump are rotary pumps and reciprocating pumps.
Moreover, water
pump is a reciprocating positive displacement pump that have an expanding
cavity on the suction side and a decreasing cavity on the discharge side. In
water pumps, the liquid flows into the pumps as the cavity on the suction side
expands and then the liquid flows out of the discharge as the cavity collapses
providing water in a pail.
A snowball picks up speed as it rolls down the mountain.<em> (D)</em>
Since the description includes acceleration ("picks up speed"), we know that the forces on the snowball must be unbalanced.
The process of formation of a reddish-brown substance on the surface of the iron objects in the presence of flaky moisture and air is called rusting.
