1. [2/2 Points] A ship on a large river approaches a bridge, and the captain notices that the ship is about a foot too tall to fit under the bridge. A crew member suggests pumping water from the river...

1.
[2/2 Points]
A ship on a large river approaches a
idge, and the captain notices that the ship is about a foot too tall to fit under the
idge. A crew member suggests pumping water from the river into an empty tank on the ship. Would this help?
YesNo    
Why or why not?
It would help because pumping water from the river into the ship lowers the river height.It would help because pumping water into the ship makes the ship more dense, causing it to displace more water and ride lower in the water.    It would not help because the water is still part of the ship–river system, whether the water is in the river or in a tank on the ship.It would not help because pumping water into the ship makes the ship less dense, causing it to displace less water and ride higher in the water.
2.
[–/2 Points]
Pistons are fitted to two cylindrical chambers connected through a horizontal tube to form a hydraulic system. The piston chambers and the connecting tube are filled with an incompressible fluid. The cross-sectional areas of piston 1 and piston 2 are A1 and A2, respectively. A force F1 is exerted on piston 1. Rank the resultant force F2 on piston 2 that results from the combinations of F1, A1, and A2 given from greatest to smallest. If any of the combinations yield the same force, give them the same ranking. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols.)
a. F1 = 6.0 N; A1 = 0.9 m2; and A2 = 1.8 m2
. F1 = 3.0 N; A1 = 0.9 m2; and A2 = 0.45 m2
c. F1 = 3.0 N; A1 = 1.8 m2; and A2 = 3.6 m2
d. F1 = 6.0 N; A1 = 0.45 m2; and A2 = 1.8 m2
e. F1 = 6.0 N; A1 = 0.45 m2; and A2 = 0.9 m2
f. F1 = 3.0 N; A1 = 1.8 m2; and A2 = 0.9 m2
 
3.
[–/2 Points]
A bicycle tire pump has a piston with area 0.31 in2. If a person exerts a force of 21 lb on the piston while inflating a tire, what pressure does this produce on the air in the pump?
 psi
  
4.
[–/2 Points]
A large truck tire is inflated to a gauge pressure of 86 psi. The total area of one sidewall of the tire is 1,270 in2. What is the net outward force (in lb) on the sidewall because of the air pressure? (Enter the magnitude.)
 l
 
5.
[–/2 Points]
A viewing window on the side of a large tank at a public aquarium measures 33 in. by 43 in. The average gauge pressure from the water is 7 psi. What is the total outward force on the window?
 l
 
6.
[–/2 Points]
The total mass of the hydrogen gas in the Hindenburg zeppelin was 18,000 kg. What volume did the hydrogen occupy? (Assume that the temperature of the hydrogen was 0°C and that it was at a pressure of 1 atm.)
 m3
 
7.
[–/2 Points]
A large balloon used to sample the upper atmosphere is filled with 610 m3 of hydrogen. What is the mass of the hydrogen (in kg)?
 kg
 
8.
[–/2 Points]
Find the gauge pressure (in psi) at the bottom of a freshwater swimming pool that is 12.2 ft deep.
 psi
 
9.
[–/2 Points]
The depth of the Pacific Ocean in the Mariana Trench is 36,198 ft. What is the gauge pressure at this depth?
 psi
  
10.
[–/2 Points]
An ebony log with volume 16.4 ft3 is submerged in water. What is the buoyant force on it (in lb)? (Enter the magnitude.)
 l
11.
[–/2 Points]
An empty storage tank has a volume of 1,910 ft3. What is the buoyant force exerted on it by the air? (Assume the air is at 0°C and 1 atm.)
 l
  
12.
[–/2 Points]
A modern-day zeppelin holds 7,290 m3 of helium. Compute its maximum payload at sea level. (Assume the helium and air to be at 0°C and 1 atm.)
 N
 
13.
[–/2 Points]
A boat (with a flat bottom) and its cargo weigh 7,000 N. The area of the boat's bottom is 5 m2. How far below the surface of the water is the boat's bottom when it is floating in water?
 m
  
14.
[–/2 Points]
A scale reads 326 N when a piece of iron is hanging from it. What does it read (in N) when it is lowered so that the iron is submerged in water?
 N
 
15.
[2/2 Points]
A rectangular block of ice with dimensions 2 m by 3 m by 0.2 m floats on water. A person weighing 820 N wants to stand on the ice. Would the ice sink below the surface of the water?
YesNo    
 
16.
[–/2 Points]
A dentist's chair with a person in it weighs 1625 N. The output plunger of a hydraulic system starts to lift the chair when the dental assistant's foot exerts a force of 40 N on the input piston. Neglecting any difference in the heights of the piston and the plunger, what is the ratio of the area of the plunger to the area of the piston?
    Aplunge
    Apiston
 = 
  
17.
[–/2 Points]
The wing of an airplane has an average cross-sectional area of 13 m2 and experiences a lift force of 85,000 N. What is the average difference in the air pressure between the top and bottom of the wing?
 N/m2
 
18.
[–/2 Points]
Air flows through a heating duct with a square cross-section with 7-inch sides at a speed of 4.5 ft/s. Just before reaching an outlet in the floor of a room, the duct widens to assume a square cross-section with sides equal to 16 inches. Compute the speed of the air flowing into the room (in ft/s), assuming that we can treat the air as an incompressible fluid.
 ft/s
  
19.
[2/2 Points]
How are the concepts of pressure, force, and area related to the function of snowshoes as a person stands at rest on the snow?
Since the snowshoes have a relatively large area, they reduce the force that the person's feet apply to the snow.The wide area of the snowshoes allows the snowshoes to provide a larger force than the person's weight as the person stands on the snow; this supports the person.    Snowshoes distribute a person's weight (a force) over a larger area; this reduces the pressure from the snowshoes on the snow.
Co
ect.
 
20.
[2/2 Points]
Is it possible to measure altitude with a barometer?
Yes. As the altitude increases, the air pressure also increases, so a higher barometer reading indicates a higher altitude.No. Air pressure is constant at all elevations, so a barometer measuring air pressure is not able to give information about altitude.    Yes. As the altitude increases, the air pressure decreases, so a lower barometer reading indicates a higher altitude.
Co
ect.
 
21.
[2/2 Points]
Various objects in our daily lives are attached to windows, refrigerators, bathroom walls, and other surfaces using suction cups. How does a suction cup work?
Suction cups only work if they make use of some form of chemical adhesive. Air pressure alone cannot produce strong enough forces to hold a suction cup in place.The air molecules inside a suction cup pull the suction cup toward the surface it is attached to, holding it in place.    The pressure from the atmosphere is greater than the pressure inside the suction cup. This difference causes the suction cup to be pressed against the surface it is attached to.
Co
ect.
 
22.
[2/2 Points]
Use the following table to determine which of the other materials from the list would float if placed in a container of gasoline. Select all co
ect answers.
    Substance
    Density
(kg/m3)
    diamond
    3,400
    ebony wood
    1,200
    gasoline
    680
    juniper wood
    560
    lead
    11,340
    Styrofoam
    37
diamondebony woodjuniper woodleadStyrofoamNone of the above materials would float; they are all solids and would sink in a liquid.
 
23.
[2/2 Points]
A person does the back float in a freshwater lake and later does the same in the ocean. In which case is more of the person's body above the water line?
The person will float with more of her body above water in freshwater.The person will float with more of her body above water in the ocean.    Since both situations involve the person floating in a solution that is primarily water, there will not be a difference between the two cases.
Co
ect. The density of seawater is about three percent higher than that of pure water. This means that it would take a smaller volume of displaced water to have the same weight, thus providing the necessary buoyant force to allow the person to float.
 
24.
[–/2 Points]
A metal bowl with a weight of 1.65 N is placed in a larger kitchen container filled with corn oil. How much corn oil must the bowl displace in order to float? For reference, the mass density of corn oil is about 900 g/liter and its weight density is about 8.82 N/liter. Please give your answer in liters.
 liters
 
25.
[2/2 Points]
While an airplane is in flight, the pressure along the top of the wing is lower than the pressure along the bottom of the wing, providing a lift force. How does the speed of the air going past the top of the wing compare to the speed of the air going past the bottom of the wing?
The speed of the air going past the top of the wing is greater than the speed of the air passing the bottom of the wing.Since the wings are attached to the plane they are both moving through the air at the same speed and the air moving above or below the wings is passing the wing at the same speed.    The speed of the air is greater when passing the bottom of the wing than it is when passing the top of the wing.
Co
ect. Because of this difference in speeds and Bernoulli's principle, we expect a lower pressure in the faster-moving air above the wing which allows for a lift force.
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