Question

Why a spray pump dip in water is filled with liquid when the piston is pulled up
A. force applied by piston on water sucks in the water
B. force applied by water on a spray pump is more than the pull force.
C. pressure inside the spray pump reduces when the piston is pulled back forcing water into the cylinder.
D. pressure inside the spray pump increases when the piston is pulled back forcing water into the cylinder.

Answer 1

Hint: Venturi effect can be used to explain the rise of water inside a spray pump when the pistol is pulled up. The effect shows that as the pressure decreases, the velocity of the flow into that tube increases. The pressure variation is the major thing causing the process to take place.

Complete answer:
When the piston of the spray pump is pulled up by the help of an external force. This will increase the area of the air in the tube. As we all know the pressure is inversely proportional to the area of the space. So here also as the area is getting increased, there will be a pressure drop inside the tube. This will in a way create a vacuum in the spray tube, which is the least pressure possible. Water outside the spray pump will be higher as it is under the influence of atmospheric pressure. This pressure difference will cause liquids to flow from the high Pressure to Low Pressure. Therefore the water enters the cylinder of the spray pump.

So, the correct answer is “Option C”.

Note:
A spray-bottle is having a trigger lever, which is activating the small pump near to it. This pump has been attached to a plastic tube that is taking the liquid to be filled from the bottom of the reservoir. As the piston is pushed down, area gets reduced, fluid gets out of the pump.