Chapter 10: Fluids Flashcards
At a fixed depth within a fluid at rest, the pressure pushing upward is _______
equal to the pressure pushing downward
While swimming near the bottom of a pool, you let out a small bubble of air. As the bubble rises toward the surface, what happens to its diameter?
Its diameter increases slightly
What is the difference between the pressures inside and outside a tire called?
gauge pressure
The three common phases of matter are _________
solid, liquid, and gas.
Density is _________
proportional to mass and inversely proportional to volume.
Substance A has a density of 3.0 g/cm3 and substance B has a density of 4.0 g/cm3. In order to obtain equal masses of these two substances, the ratio of the volume of A to the volume of B will be equal to
4:3
Which of the following is not a unit of pressure?
N/m
Consider three drinking glasses. All three have the same area base, and all three are filled to the same depth with water. Glass A is cylindrical. Glass B is wider at the top than at the bottom, and so holds more water than A. Glass C is narrower at the top than at the bottom, and so holds less water than A. Which glass has the greatest liquid pressure at the bottom?
All three have equal pressure
50 cm3 of wood is floating on water, and 50 cm3 of iron is totally submerged. Which has the greater buoyant force on it?
the iron
Salt water has greater density than fresh water. A boat floats in both fresh water and in salt water. Where is the buoyant force greater on the boat?
buoyant force is the same in both
An ideal fluid flows at 12 m/s in a horizontal pipe. If the pipe widens to twice its original radius, what is the flow speed in the wider section?
3.0 m/s
A sky diver falls through the air at terminal velocity. The force of air resistance on him is _________
equal to his weight
A plastic block of dimensions 2.00 cm x 3.00 cm x 4.00 cm has a mass of 30.0 g. What is its density?
1.25 g/cm^3
A liquid has a specific gravity of 0.357. What is its density?
357 kg/m^3
A person weighing 900 N is standing on snowshoes. Each snowshoe has area 2500 cm2. What is the pressure on the snow?
1800 N/m^2
How much pressure (absolute) must a submarine withstand at a depth of 120.0 m in the ocean?
1310 kPa
A 1.0-m3 object floats in water with 20% of it above the waterline. What does the object weigh out of the water?
7840 N
A solid object floats in water with three-fourths of its volume beneath the surface. What is the object’s density?
750 kg/m^3
Liquid flows through a 4.0 cm diameter pipe at 1.0 m/s. There is a 2.0 cm diameter restriction in the line. What is the velocity in this restriction?
4.0 m/s
A 500-N weight sits on the small piston of a hydraulic machine. The small piston has an area of 2.0 cm2. If the large piston has an area of 40 cm2, how much weight can the large piston support?
10000 N
A block of metal weighs 40 N in air and 30 N in water. What is the buoyant force of the water?
10 N
If the density of gold is 19.3 x 10^3 kg/m3, what buoyant force does a 0.60-kg gold crown experience when it is immersed in water?
- 30 N
A steel ball sinks in water but floats in a pool of mercury. Where is the buoyant force on the ball greater?
floating on the mercury
As the speed of a moving fluid increases, the pressure in the fluid __________
decreases
Water flows through a pipe. The diameter of the pipe at point B is larger than at point A. Where is the water pressure greatest?
point B
When you blow some air above a paper strip, the paper rises. This is because ________
the air above the paper moves faster and the pressure is lower
You are walking out on frozen Lake Bemidji during winter and you begin to hear the ice cracking beneath you. What is your best strategy for getting off the ice safely?
Lie down flat on the ice and crawl toward shoree
because pressure is decreased on the ice
Three containers are filled with water to the same height and have the same surface area at the base, but the total weight of water is different for each. Which container has the greatest total force acting on its base?
All three are equal
Thermometers often use mercury or alcohol in a thin glass tube, but barometers never use alcohol. Why?
mercury is denser than alcohol
When you drink liquid through a straw, which of the items listed below is primarily responsible for how the straw works?
atmospheric pressure
Both require the same force, difference in pressure between the top and bottom of both bricks is the same
A boat carrying a large chunk of lead is floating on a small pond. The chunk is then thrown overboard and sinks. What happens to the water level in the pond (with respect to the shore)?
It lowers
Blood pressure would be higher
smoke rises more rapidly in the chimney
