Question

When the plunger is pressed down over the sink, it forces air into the drain and increases the air pressure on it?

Answer 1

Answer:

When you press the plunger down, it forces air into the drain and increases the atmospheric pressure on it. If the item is dislodged, the pressurized air is free to travel throughout the rest of the piping. When you then pull back up on the plunger, the vacuum created will force anything inside the tube to be forced upwards.

Boyle's law is:

p1V1=p2V2

1=plunger not depressed

2=plunger depressed