constant speed. The creature rears its head above the water and it is...a rubber tire! (a) If the tire is made entirely of hard
rubber, with volume 6800 cm^3 , and density 1190 kg/m^3 , then what is the tension on your fishing line after you pull the tire out
of the water? Assume that the tire is made entirely of rubber, it is a tire (not an inner tube), and it is punctured so you are not
pulling up any water. (b) What is the tension on your fishing line before you pull the tire out of the water? Ignore any drag
forces from the water.
(a) N
(b) N8.2 You are fishing off a bridge and feel a tug on the vertical line. This time, your lucky catch is an old boot. (a) Assume that the
boot is not punctured, so that as you lift it out of the water at constant speed, you haul up one bootful, or 7500 cm^3 , of water
along with the boot. If the neoprene rubber making up the boot has volume 435 cm^3 and density 1240 kg/m^3 , then what is the
tension on your fishing line after you pull the boot out of the water? (b) What is the tension in your fishing line before you pull
the boot out of the water? Ignore any drag forces.
(a) N
(b) NSection 9 - Sample problem: buoyancy of an iceberg
9.1 A shipwrecked mariner is stranded on a desert island. He seals a plea for rescue in a 1.00 liter bottle, corks it up, and throws
it into the sea. If the mass of the bottle, plus the message and the air inside, is 0.451 kg, what percentage of the volume of the
bottle is submerged as it bobs away? Take the density of seawater to be 1030 kg/m^3. For simplicity, assume the bottle and its
contents have a uniform density.
%9.2 (a) A block of balsa wood is placed in water. The density of the wood is 125 kg/m^3. What percentage of the block is
submerged? (b) A block of maple wood is placed in water. The density of the wood is 683 kg/m^3. What percentage of the
block is submerged? (c) A block of ebony wood is placed in water. The density of the wood is 1200 kg/m^3. What percentage
of the block is submerged?
(a) %
(b) %
(c) %Section 10 - Interactive problem: Eureka!
10.1 Use the information given in the interactive problem in this section to determine which crown is not made of pure gold.
Confirm your answer by using the simulation.
The 3.20 kg crown
The 2.70 kg crownSection 11 - Pascal’s principle
11.1 An automobile having a mass of 1750 kg is placed on a hydraulic lift in a garage. The piston lifting the car is 0.246 m in
diameter. A mechanic attaches a pumping mechanism to a much smaller piston, 1.50 cm in diameter, which is connected by
hydraulic lines to the lift. She pumps the handle up and down, slowly lifting the car. What is the force exerted on the small
piston during each downward stroke?
N
Section 13 - Fluid continuity
13.1 An incompressible fluid flows through a circular pipe at a speed of 15.0 m/s. The radius of the pipe is 5.00 cm. There is a
constriction of the pipe where the radius is only 3.20 cm. How fast must the fluid flow through the constricted region?
m/s
13.2 The open end of a garden hose is directed horizontally, at a height of 1.25 m above the ground. Water issues from the hose
and follows a falling parabolic trajectory to strike the ground 2.41 m away. A gardener holding the hose wishes to water some
plants that are 5.12 m distant. What fraction of the hose end should she cover with her thumb? Assume that she continues to
hold the hose end horizontally at the same height, and be careful to tell the fraction covered, not the fraction left open.
Section 14 - Bernoulli’s equation
14.1 A stream of water is flowing through the horizontal configuration shown. The speeds v 1 and v 2 are 2.95 m/s and 5.35 m/s,
respectively. The pressure P 2 is 7.36×10^4 Pa. What is P 1? (Hint: the numbers on the pressure dials are not correct - that