Physics 2 fall final

Which has more mass, a mole of CO gas or a mole of O2 gas? A. CO B. O2

B

Is there a point between a 10 nC charge and a 20 nC charge at which the electric field is zero?

yes

The number of atoms in a container is increased by a factor of 3 while the temperature is held constant. What happens to the pressure? A. The pressure decreases by a factor of 6. B. The pressure decreases by a factor of 3. C. The pressure stays the same. D. The pressure increases by a factor of 3. E. The pressure increases by a factor of 6.

D

The positive charge in (Figure 1) is +Q. What is the negative charge if the electric field at the dot is zero?

-4Q

Imagine a square column of the atmosphere, 10 m on a side, that extends all the way to the top of the atmosphere. How much does this column of air weigh in newtons?

10,000,000 N

A 10 nC charge sits at a point in space where the magnitude of the electric field is 1400 N/C . What will the magnitude of the field be if the 10 nC charge is replaced by a 20 nC charge? Assume the system is big enough to consider the charges as small test charges.

1400 N/C

Two charged particles are separated by 10 cm. Suppose the charge on each particle is quadrupled. By what factor does the electric force between the particles change?

16

A small positive charge q experiences a force of magnitude F1 when placed at point 1 in (Figure 1). What is the magnitude of the force on a charge 3q at point 1?

3 F

A small positive charge q experiences a force of magnitude F1 when placed at point 1 in (Figure 1). What is the magnitude of the force on charge q at point 3?

3 F

A small positive charge q experiences a force of magnitude F1 when placed at point 1 in (Figure 1). What is the magnitude of the force on a charge 2q at point 2?

4 F

A small positive charge q experiences a force of magnitude F1 when placed at point 1 in (Figure 1). What is the magnitude of the force on a charge −2q at point 2?

4 F

Object 1 has an irregular shape. Its density is 4000 kg/m3 . Object 3 has the same mass and the same shape as object 1, but its size in all three dimensions is twice that of object 1. What is the density of object 3?

500 kg/m3

Object 1 has an irregular shape. Its density is 4000 kg/m3 .Object 2 has the same shape and dimensions as object 1, but it is twice as massive. What is the density of object 2?

8000 kg/m3

(Figure 1) shows a 100 g block of copper (ρ = 8900 kg/m3 ) and a 100 g block of aluminum (ρ = 2700 kg/m3 ) connected by a massless string that runs over two massless, frictionless pulleys. The two blocks exactly balance, since they have the same mass. Now suppose that the whole system is submerged in water. What will happen? A. The copper block will fall, the aluminum block will rise. B. The aluminum block will fall, the copper block will rise. C. Nothing will change. D. Both blocks will rise.

A

A 15-m-long garden hose has an inner diameter of 2.5 cm. One end is connected to a spigot; 20∘C waters flow from the other end at a rate of 1.2 L/s. What is the gauge pressure at the spigot end of the hose? A. 1900 Pa B. 2700 Pa C. 4200 Pa D. 5800 Pa E. 7300 Pa

A

A cup of water is heated with a heating coil that delivers 100 W of heat. In one minute, the temperature of the water rises by 23 ∘C. What is the mass of the water? A. 62 g B. 120 g C. 620 g D. 1.2 kg

A

A gas is compressed by an adiabatic process that decreases its volume by a factor of 2. In this process, the pressure A. increases by a factor of more than 2. B. does not change. C. increases by a factor of 2. D. increases by a factor of less than 2.

A

A large beaker of water is filled to its rim with water. A block of wood is then carefully lowered into the beaker until the block is floating. In this process, some water is pushed over the edge and collects in a tray. The weight of the water in the tray is A. equal to the weight of the block. B. greater than the weight of the block. C. less than the weight of the block.

A

All the charges in (Figure 1) have the same magnitude. In which case does the electric field at the dot have the largest magnitude? A. A B. B C. C D. D

A

Approximately how much energy would be required to raise the temperature of the top layer of the oceans by 1∘C? (1 m3 of water has a mass of 1000 kg.) A. 1×1024 J B. 1×1015 J C. 1×1021 J D. 1×1018 J

A

Does the difference between the two readings decrease, increase, or remain the same? A. The difference decreases. B. The difference increases. C. The difference remains the same. D. More information is needed to answer.

A

If so, which charge is this point closer to? A. 10 nC B. 20 nC

A

In (Figure 1), is pA larger, smaller, or equal to pB? Choose the correct explanation. A. Two points on a horizontal line, connected by a single liquid in hydrostatic equilibrium, are at the same pressure. pA=pB. B. Two points on any line, connected by a single liquid in hydrostatic equilibrium, are at the same pressure. pA=pB. C. Point A has to support the weight of the ship, while point B does not. pA>pB. D. The ship is lighter that the water since it doesn't go down. Point A has to support the weight of the ship, while point B has to support the water. pA<pB.

A

Suppose you do a calorimetry experiment to measure the specific heat of a penny. You take a number of pennies, measure their mass, heat them to a known temperature, and then drop them into a container of water at a known temperature. You then deduce the specific heat of a penny by measuring the temperature change of the water. Unfortunately, you didn't realize that you dropped one penny on the floor while transferring them to the water. How will this affect your calculation of the penny's heat? A. This will cause you to underestimate the specific heat. B. This will cause you to overestimate the specific heat. C. This will not affect your calculation of specific heat.

A

Water's coefficient of expansion varies with temperature (Figure 2). For water at 2∘C, an increase in temperature of 1∘C would cause the volume to A. decrease. B. stay the same. C. increase.

A

Which has the greater density, 5 g of mercury or 4000 g of water? A. 5 g of mercury B. 4000 g of water

A

A beaker of water rests on a scale. A metal ball is then lowered into the beaker using a string tied to the ball. The ball doesn't touch the sides or bottom of the beaker, and no water spills from the beaker. Does the scale reading decrease, increase, or stay the same? A. The scale reading decreases.The fluid exerts an upward force on the ball. Thus, by Newton's third law, the ball exerts a downward force on the fluid. This downward force decreases the scale reading. B. The scale reading increases.The fluid exerts an upward force on the ball. Thus, by Newton's third law, the ball exerts a downward force on the fluid. This downward force raises the scale reading. C. The scale reading stays the same. The fluid exerts an upward force on the ball which is equal to the ball's weight. There is no force to change the scale reading. D. The scale reading stays the same. The tension force of the string always balances the ball, so the ball doesn't affect the scale reading.

B

A metal rod A and a metal sphere B, on insulating stands, touch each other as shown in (Figure 1). They are originally neutral. A positively charged rod is brought near (but not touching) the far end of A. While the charged rod is still close, A and B are separated. The charged rod is then withdrawn. Is the sphere then positively charged, negatively charged, or neutral? A. neutral B. positively charged C. Negatively charged

B

All the charges in (Figure 1) have the same magnitude. In which case does the electric field at the dot have the largest magnitude? A. A B. B C. C D. D

B

An 9.0 lb bowling ball has a diameter of 8.5 inches. When lowered into water, this ball will A. have neutral buoyancy. B. float. C. sink.

B

An object floats in water, with 80 % of its volume submerged. What is its approximate density? A. 200 kg/m3 B. 800 kg/m3 C. 1000 kg/m3 D. 1200 kg/m3

B

For the gauge that reads gauge pressure, does the pressure reading decrease, increase, or remain the same? A. The pressure reading decreases. B. The pressure reading increases. C. The pressure reading remains the same. D. More information is needed to answer.

B

If the top 500 m of ocean water increased in temperature from 17 ∘C to 18 ∘C, what would be the resulting rise in ocean height? A. 0.22 m B. 0.11 m C. 0.88 m D. 0.44 m

B

Is there an air flow through the house? If so, does the air flow in the window and out the chimney, or in the chimney and out the window? Choose the correct explanations. A. The pressure is increased at the chimney due to the movement of the wind above. Thus, the air will flow in the chimney and out the window. B. The pressure is reduced at the chimney due to the movement of the wind above. Thus, the air will flow in the window and out the chimney. C. The pressure is increased at the chimney due to the movement of the wind above. Thus, the air will flow in the window and out the chimney. D. The pressure is reduced at the chimney due to the movement of the wind above. Thus, the air will flow in the chimney and out the window. E. The pressures at the chimney and the window are the same. Thus, the air will not flow.

B

Masses A and B rest on very light pistons that enclose a fluid, as shown in (Figure 1). There is no friction between the pistons and the cylinders they fit inside. Which mass is greater? A. Mass A is greater. B. Mass B is greater. C. Mass A and mass B are the same. D. The answer depends on the density of the fluid.

B

Steam at 100∘C causes worse burns than liquid water at 100∘C. This is because A. The steam is hotter than the water. B. Heat is transferred to the skin as steam condenses. C. Steam has a higher specific heat than water. D. Evaporation of liquid water on the skin causes cooling.

B

Suppose a syringe is being used to squirt water as shown in (Figure 1). The water is ejected from the nozzle at 10 m/s . At what speed is the plunger of the syringe being depressed? A. 0.01 m/s B. 0.1 m/s C. 1.0 m/s D. 10 m/s

B

Suppose the 650 W of radiation emitted in a microwave oven is absorbed by 320 g of water in a very lightweight cup. Approximately how long will it take to heat the water from 20 ∘C to 50 ∘C? A. 31 s B. 62 s C. 93 s D. 120 s

B

The thermal energy of a container of helium gas is halved. What happens to the temperature, in kelvin? A. It decreases to one-fourth its initial value. B. It decreases to one-half its initial value. C. It stays the same. D. It increases to twice its initial value.

B

Three identical beakers each hold 1000 g of water at 20 ∘C. 100 g of liquid water at 0∘C is added to the first beaker, 100 g of ice at 0 ∘C is added to the second beaker, and the third beaker gets 100 g of aluminum at 0∘C. The contents of which container end up at the lowest final temperature? A. The first beaker. B. The second beaker. C. The third beaker. D. All end up at the same temperature.

B

Two lightweight, electrically neutral conducting balls hang from threads. Note that parts A through D are independent; these are not actions taken in sequence. Choose the diagram that shows how the balls hang after both are touched by a negatively charged rod, but ball 2 picks up more charge than ball 1. A. A B. B C. C D. D E. E

B

Two lightweight, electrically neutral conducting balls hang from threads. Note that parts A through D are independent; these are not actions taken in sequence. Choose the diagram in (Figure 1) that shows how the balls hang after both are touched by a negatively charged rod. A. A B. B C. C D. D E. E

B

What would happen to the volume of air in the swim bladder if the fish didn't change the amount of air in it? A. The volume of air would decrease because of the decreasing pressure. B. The volume of air would decrease because of the increasing pressure. C. The volume of air would increase because of the decreasing pressure. D. The volume of air would increase because of the increasing pressure.

B

40000 J of heat is added to 1.00 kg of ice at -10 ∘C. How much ice melts? A. 8.50×10−3 kg B. 1.42×10−2 kg C. 5.74×10−2 kg D. 0.120 kg

C

A gas is compressed by an isothermal process that decreases its volume by a factor of 2. In this process, the pressure A. increases by a factor of less than 2. B. increases by a factor of more than 2. C. does not change. D. increases by a factor of 2.

D

The ocean is mostly heated from the top, by light from the sun. The warmer surface water doesn't mix much with the colder deep ocean water. This lack of mixing can be ascribed to a lack of A. radiation. B. conduction. C. evaporation. D. convection.

D

To explore the bottom of a 10-m-deep lake, your friend Tom proposes to get a long garden hose, put one end on land and the other in his mouth for breathing underwater, and descend into the depths. Susan, who overhears the conversation, reacts with horror and warns Tom that he will not be able to inhale when he is at the lake bottom. Why is Susan so worried? A. The pressure at a depth of 10 m is 3.5×105Pa. This is almost 3.5 times greater than atmospheric pressure. But he air pressure in the hose will be only slightly higher than atmospheric pressure, because the density of air is so low. So Tom will have great difficulty breathing in the low-pressure air when the large pressure of the water is pressing in on his chest. B. The pressure at a depth of 10 m is 2.5×105Pa. This is almost 2.5 times greater than atmospheric pressure. But he air pressure in the hose will be only slightly higher than atmospheric pressure, because the density of air is so low. So Tom will have great difficulty breathing in the low-pressure air when the large pressure of the water is pressing in on his chest. C. The pressure at a depth of 10 m is 3×105Pa. This is almost three times greater than atmospheric pressure. But he air pressure in the hose will be only slightly higher than atmospheric pressure, because the density of air is so low. So Tom will have great difficulty breathing in the low-pressure air when the large pressure of the water is pressing in on his chest. D. The pressure at a depth of 10 m is 2×105Pa. This is almost two times greater than atmospheric pressure. But he air pressure in the hose will be only slightly higher than atmospheric pressure, because the density of air is so low. So Tom will have great difficulty breathing in the low-pressure air when the large pressure of the water is pressing in on his chest.

D

Water flows through a 4.0-cm-diameter horizontal pipe at a speed of 1.3 m/s. The pipe then narrows down to a diameter of 2.0 cm. Ignoring viscosity, what is the pressure difference between the wide and narrow sections of the pipe? A. 850 Pa B. 3400 Pa C. 9300 Pa D. 12700 Pa E. 13500 Pa

D

When you place an egg in water, it sinks. If you add salt to the water, after some time the egg floats. Choose the correct explanation. A. Adding salt to the water decreases its density. When the density of the water matches that of the egg, the egg becomes neutrally buoyant and floats. B. Adding salt to the water increases its volume. When the volume of the water matches that of the egg, the egg becomes neutrally buoyant and floats. C. Adding salt to the water decreases its volume. When the volume of the water matches that of the egg, the egg becomes neutrally buoyant and floats. D. Adding salt to the water increases its density. When the density of the water matches that of the egg, the egg becomes neutrally buoyant and floats.

D

Will the fish need to add or remove gas from the swim bladder to maintain its neutral buoyancy? A. The fish will need to add gas, otherwise the fish will go deeper with decreasing speed. B. The fish will need to remove gas, otherwise the fish will go deeper with decreasing speed. C. The fish will need to remove gas, otherwise the fish will go deeper with increasing speed. D. The fish will need to add gas, otherwise the fish will go deeper with increasing speed.

D

100 g of ice at 0∘C and 100 g of steam at 100∘C interact thermally in a well-insulated container. What is the final state of the system? A. An ice-water mixture at 0∘C B. Water at a temperature between 0∘C and 50∘C. C. Water at 50∘C. D. Water at a temperature between 50∘C and 100∘C. E. A water-steam mixture at 100∘C.

E

The water of the Dead Sea is extremely salty, which gives it a very high density of 1240 kg/m3. Explain why a person floats much higher in the Dead Sea than in ordinary water as shown in (Figure 1). Adding salt to water _______________ its density. How high a person floats in the water depends on the ratio of the density of the person to the density of the water. The density of the person _______________. With denser water, however, the person would ____________________ in the water.

increases, doesn't change, float higher

Is there a point between a 10 nC charge and a -20 nC charge at which the electric field is zero? (Note the change of sign of the second charge.)

no

A positively charged particle is in the center of a parallel-plate capacitor that has charge ±Q on its plates. Suppose the distance between the plates is doubled, with the charged particle remaining in the center. Does the force on this particle increase, decrease, or stay the same? Explain. If we assume the size of the parallel plates is large compared to the separation, then doubling the plate separation will ____________________________ the field inside the capacitor. That means this transformation will _______________________________ the force.

not change; not change

Objects A, B, and C in (Figure 1) have the same volume. Rank in order, from largest to smallest, the sizes of the buoyant forces FA, FB, and FC on A, B, and C.

A=B=C

Rank in order, from largest to smallest, the pressures at A, B, and C in (Figure 1).

A=B=C

A heavy lead block and a light aluminum block of equal size sit at rest at the bottom of a pool of water. Is the buoyant force on the lead block greater than, less than, or equal to the buoyant force on the aluminum block? Choose the best explanation. A. For objects that are completely submerged the buoyant force is proportional to the mass of the object. The buoyant force on the lead block is greater than the buoyant force on the aluminum block. B. For objects that are completely submerged the buoyant force is inversely proportional to the density of the object. Since the two blocks are the same size (volume), then the buoyant force on the lead block is less than the buoyant force on the aluminum block. C. For objects that are completely submerged the buoyant force is proportional to the volume of the object. Since the two blocks are the same size (volume), then the buoyant force is the same on both blocks. D. For objects that are completely submerged the buoyant force is proportional to the density of the object. Since the two blocks are the same size (volume), then the buoyant force on the lead block is greater than the buoyant force on the aluminum block.

C

A tire is inflated to a gauge pressure of 35 psi . The absolute pressure in the tire is A. Less than 35 psi . B. Equal to 35 psi . C. Greater than 35 psi .

C

For the gauge that reads absolute pressure in the tank, does the pressure reading decrease, increase, or remain the same? A. The pressure reading decreases. B. The pressure reading increases. C. The pressure reading remains the same. D. More information is needed to answer.

C

Is it possible for a fluid in a tube to flow in the direction from low pressure to high pressure? A. No. According to Pascal's principle, the pressure is the same at all points of the fluid. B. Yes. If a horizontal pipe has a constant diameter, the fluid will flow at constant speed in it, for example, from left to right. According to Bernoulli's principle, the pressure in the right part of the fluid will be higher than in the left part. C. Yes. If a horizontal pipe has an increase in its diameter, the fluid will flow slower in this wider part. According to Bernoulli's principle, the pressure in this slow-moving part of the fluid will be higher than in the upstream, fast-moving part. D. No. According to Bernoulli's principle, the fluid always flows from high pressure to low pressure.

C

Two lightweight, electrically neutral conducting balls hang from threads. Note that parts A through D are independent; these are not actions taken in sequence. Choose the diagram that shows how the balls hang after only ball 1 is touched by a negatively charged rod. A. A B. B C. C D. D E. E

C

Two lightweight, electrically neutral conducting balls hang from threads. Note that parts A through D are independent; these are not actions taken in sequence. Choose the diagram that shows how the balls hang after ball 1 is touched by a negatively charged rod, and ball 2 is touched by a positively charged rod. A. A B. B C. C D. D E. E

C

You are given two metal spheres on portable insulating stands, a glass rod, and a piece of silk. How to give the spheres exactly equal but opposite charges? A. Put the two metal spheres in contact with each other. Then rub the glass rod on the silk to charge the rod positively (hence to charge piece of silk negatively). Touch one of the spheres with the glass rod then separate the spheres. Touch another sphere with the piece of silk. B. Make sure spheres are not in contact with each other. Rub the glass rod on the silk to charge the rod positively (hence to charge piece of silk negatively). Bring the rod near, but not touching, one of the spheres. Do the same with piece of silk and another sphere. Remove the galss rod and the piece of silk. C. Put the two metal spheres in contact with each other. Then rub the glass rod on the silk to charge the rod positively (hence to charge piece of silk negatively). Bring the rod near, but not touching, one of the spheres. Separate the spheres and remove the rod. D. Make sure spheres are not in contact with each other. Rub the glass rod on the silk to charge the rod positively (hence to charge piece of silk negatively). Touch one of the spheres with the glass rod then touch another one with the piece of silk.

C

If you dive under-water, you notice an uncomfortable pressure on your eardrums due to the increased pressure. The human eardrum has an area of about 70 mm2 (7×10−5m2), and it can sustain a force of about 7 N without rupturing. If your body had no means of balancing the extra pressure (which, in reality, it does), what would be the maximum depth you could dive without rupturing your eardrum? A. 0.3 m B. 1 m C. 3 m D. 10 m

D. 10 m

Refer to (Figure 1). Rank in order, from largest to smallest, the pressures at D, E, and F.

D>F>E