fluids and thermo review penner 1

The figure shows pipe 1 of cross-sectional area A1 and pipe 2 of area A2, which merge into pipe 3 of area A3.  Water in pipes 1 and 2 flow with speed v1 and v2, respectively.  What is the speed in pipe 3?

•  $\frac{A_1v_1+A_2v_2}{A_3}$  

•  $\frac{A_1v_1-A_2v_2}{A_3}$  

•  $\frac{\left(A_1+A_2\right)\left(v_1+v_2\right)}{A_3}$  

•  $A_3\left(\frac{v_1}{A_1}+\frac{v_2}{A_2}\right)$  

A hollow rectangular box is filled with a liquid and can be placed in any of the three orientations shown here. In which orientation will the fluid pressure at the bottom of the box be greatest and why?

• X, because pressure at the bottom of a fluid is greater when the vertical height of the fluid is greater

• Y, because pressure at the bottom of a fluid is greater when the width time the height of the fluid is greater

• Z, because pressure at the bottom of a fluid is greater when the area of the bottom surface is greater

• All have the same pressure because the weight of the fluid is the same in each case

An ideal gas is taken from initial state i at pressure Po and volume Vo to final state f at pressure 2Po and volume 2Vo. The figures below represent four possible processes by which the gas can be taken from state i to state f. For which process is the work done by the gas greatest?

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Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

In an experiment, students recorded the pressure and volume of a sample of ideal gas as its temperature was varied, as shown on the graph. Which of the following ranks the internal energy, U, of the gas at the labeled points from greatest to least?

• $\left(U_B=U_C\right)>U_D>U_A$

• $\left(U_C=U_D\right)>U_B>U_A$

• $\left(U_C=U_D\right)>U_A>U_B$

• $U_D>\left(U_C=U_A\right)>U_B$

Tags

NGSS.HS-PS3-1

An ideal gas with molecules of mass m is contained in a cube with sides of area A. The average vertical component of the velocity of the gas molecules is v, and N molecules hit the side of the cube in a time t.  What is the pressure exerted by the gas on the bottom of the cube?

• mv/At

• 2mv/At

• Nmv/At

• 2Nmv/At

A sample of gas is in a container of fixed volume. The pressure of the gas is measured as its temperature is increased, as shown on the graph. Which of the following will be true if the container volume is reduced to half the original value and the experiment repeated?

• The graph will still show a linear relationship that passes through the origin, but with a smaller slope

• The graph will still show a linear relationship that passes through the origin, but with a larger slope

• The graph will still show a linear relationship, but not pass through the origin

• The graph will not show a linear relationship, but it will pass through the origin

Two containers, each holding a different gas, are brought into thermal contact. The gas atoms in container X have twice the mass and half the average speed of the gas atoms in container Y. Which of the following best describes the energy transfer by thermal conduction, if any, between the two containers?

• There is a net energy transfer from container X to container Y

• There is a net energy transfer from container Y to container X

• There is no net energy transfer between containers, because no atoms move between them

• There is no net energy transfer between containers, because energy is transferred at approximately equal rates in each direction

Tags

NGSS.HS-PS3-2

NGSS.HS-PS3-4

Students in a lab are given a plunger-syringe as shown which contains air at room temperature. Students take textbooks and place them on top one at a time, allowing the system to return to room temperature each time. Assuming air to act as an ideal gas, which of the following graphs best represents the volume of air as a function of the number of books?

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When the average speed of the molecules in a certain sample of gas is v, the absolute temperature of the gas is T. If the average speed of the gas is doubled to 2v, what is the new absolute temperature?

• $4T$

• $2T$
  

• $T$

• $\sqrt{2\ }T$

Tags

NGSS.HS-PS3-2

Water of density 1000 kg/m^3 flows at a speed of 3.0 m/s through a section of pipe of radius 0.040 m. The pipe bends upwards to 0.25 m above its original height and tapers to a radius of 0.020 m as shown. If the water pressure is 1.50e5 Pa in the lower part of the pipe, the water pressure in the upper part of the pipe is most nearly

• 0.8e5 Pa

• 1.48e5 Pa

• 1.53e5 Pa

• 2.29e5 Pa