College Physics with MasteringPhysics 7th Edition by Jerry Wilson,Anthony Buffa,Bo Lou

تمرين 111

A nurse needs to draw 20.0 cc of blood from a patient and deposit it into a small plastic container whose interior is at atmospheric pressure. He inserts the needle end of a long tube into a vein where the average gauge pressure is 30.0 mm Hg. This allows the internal pressure in the vein to push the blood into the collection container. The needle is 0.900 mm in diameter and 2.54 cm long. The long tube is wide and smooth enough that we can assume its resistance is negligible, and that all the resistance to blood flow occurs in the narrow needle. How long does it take him to collect the sample