The lower end of a long plastic straw is immersed below the surface of the water in a plastic cup. An average person sucking on the upper end of the straw can pull water into the straw to a vertical height 0111 m above the surface of the water in the cup.
(a) What is the lowest gauge pressure that the average person can achieve inside his lungs?
(b) Explain why your answer in part (a) is negative.