1. As a prank, a student's friends put a harness on him and hook him to a suction cup on the ceiling. If the student has a mass of 70 kg, what must the area of the suction cup be to support him?

2. The Mindanao Trench, off the coast of the Philippines, is the world's deepest at 11,515 m. What is the pressure at this depth? How can sea creatures live at this depth? Why is it so dangerous for submersibles to go to this depth? Sometimes biologists catch fish at this depth and bring them to the surface. If they raise the fish too quickly, they get instant sushi. How come?

3. A tube contains 12.2 cm of water. A second tube contains 15.8 cm of an unknown fluid. The pressure at the bottom of both tubes is the same but unknown. What is the density of the unknown fluid?

4. An 80-kg person lies on a 12-cm thick water mattress. Assuming that the deformation of the top of the mattress is negligible, what is the pressure at the bottom of the water?

5. A patient with no arms visits the doctor. The doctor places a blood pressure cuff around the patient's ankle and measures BP to be 235/190. If the patient's ankle is 1.42 m below where his elbow would have been, what would the reading have been at elbow height?

6. If someone your size sat on your chest you would have difficulty breathing. Now imagine you go swimming using a long straw as a snorkel. Estimate how deep underwater you could swim using the straw.

7. A hydraulic lift is used to raise a 2000-kg car 2.0 m. The base under the car has an area of 9.0 m². The other side of the area has an area of 0.010 m². What force must be exerted at that end to lift the car? What distance must the force move through?

8. A sightseeing balloon can lift a total mass of 500 kg including the balloon material, basket, and passengers but excluding the helium gas. What volume of helium is needed to lift the balloon?

9. A large balloon, filled with an unknown gas, exerts a 5.25 N force on a spring. If the volume of the balloon is 1.70 m³, what is the density of the gas. Take the density of air to be 1.21 kg/m³.

   

10. A class conducts a number of experiments on the behaviour of fluids using an instructor, a rope, a force scale, and a very large graduated cylinder. The cylinder is 3.00 m deep and has a diameter of 2.00 m. The 80-kg instructor is completely immersed in the water in the cylinder and tied to a force scale at the bottom of the cylinder as shown in the diagram below. The water in the cylinder rises 2.65 cm after the instructor is immersed.
    (a) How dense is the instructor?
    (b) What is the reading on the scale?
    

    

11. A thin steel slab is 1.0 m × 1.0m × 2.0 mm. A thicker wooden slab, t = 5.0 mm, of the same area is stuck to the steel slab. What is the density of the combined slab? How thick would the wood slab have to be for the combined steel and wood slab to just float on water?

12. An aluminum box is 1.00 m on each side with only air inside. The aluminum is 4.0 mm thick. What is the density of the box? How deep will it sink if placed in water?

13. Water leaves the exterior faucet of your house at 30 ℓ/min though a 5/8" (1.59 cm) faucet. A garden hose with a nozzle is attached. The nozzle has a diameter of 3 mm. What is the speed of the water leaving the nozzle?

14. A barrel 1.75 m high is filled to the brim with water. How far from the top would a hole have to be punched so that the stream of water would land 0.85 m from the barrel? Hint you need to know the speed at which the water leaves the barrel and then treat the water as a projectile.

    

15. A tube of fluid is shown in the diagram below. There is a hole on the side through which the fluid is pouring out. The hole has an area A. The mouth of the tube has a sealed gasket of area 3A. A gasket is a lid which is free to move up and down. The seal around the gasket keeps water from leaking out. A extra force F, besides atmospheric pressure, is applied to the gasket. The fluid is currently at a height H while the hole is at height h. Find an expression for the velocity of the fluid leaving the hole.

    

16. The 80-kg owner of a 12-cm thick 1.5 m × 2.0 m water mattress wants to drain the water. He attaches a 5/8" (1.59 cm) diameter garden hose to the mattress and hangs the other end out the window so that it lies on the ground 5.0 m below.
    a) How fast does water exit the hose? If the flow remains constant how long does it take to drain the full water mattress?
    b) To speed things up the owner lies on the mattress. Assuming that the deformation of the top of the mattress is negligible, how fast does water now exit the hose? If the flow remains constant how long does it take to drain the full water mattress?

17. In storms, it is sometimes said that the winds blew the roof off a house. Explain what really happens.

18. If blood flow to the stomach goes from 1.0 L/min to 5.0 L/min to aid digestion, by how much must the arteries dilate? Assume all other quantities stay the same.

19. A hypodermic syringe contains 15 cm³ of a solution with a viscosity of 2 × 10^-3 Pa·s. The syringe has a diameter of 1.0 cm and the needle had an inner radius of 5.0 × 10^-4 m. The needle is 3.0 cm long. The solution is injected into a patient's vein (vein pressure is 3 mm Hg). How hard must the plunger be pressed to inject the solution in 5.0 seconds?

20. Another problem with attempting to use a long straw to swim deeply under water is that you must blow out the stale air to get fresh air in. What is the smallest radius of straw you can use if you need 6.0 ℓ/min of fresh air? Assume your breathing pressure is 100 Pa.

Questions?mikec@kwantlen.bc.ca