Since the stone is travelling, the displacement cannot be constant. This leaves the last 2 choices as possibilities. Now consider the acceleration that can act on the stone. Acceleration due to gravity is the only one. That means the horizontal component of the stone has to be constant since there is no acceleration in the horizontal direction.
Correct one is b
Good luck
According to the Bernoulli's equation,the pressure difference between the wide and narrow ends of the pipe is given by
Here, 
is the velocity of water through wide ends of cylindrical pipe and 
is the velocity of water through narrow ends of cylindrical pipe.
Given, 
Now from equation continuity,
.
Here, 
and 
are cross- sectional areas of wide and narrow ends of cylindrical pipe.
As pipe is circular, so
.
At the second point, the diameter is halved, which means the radius is also halved. Therefore,
Substituting these values with the density of water is 
in pressure difference formula we get.
A windmill produces wind without electricity. wind blows on a windmill and it and that’s how it produces wind. You can put a windmill in anywhere outdoors (ex. Deserts or plains)
—————————————————————
Hope this helped you:)
