Multiple Choice

Multiple Choice Questions 1. The density of a material a. depends partly on how massive the individual atoms are that make up the material. b. depends in part on how closely packed the material’s atoms are. c. can be a useful tool in identifying the composition of an unknown substance. d. is equal to its mass divided by its volume. e. all of the above Ans: e 2. The density of a copper bar is a. greater than the density of any of the tiny grains of copper filings. b. able to be experimentally determined, while the density of copper filings cannot because it varies so much. c. equal to the density of tiny grains of copper filings. d. less than any amalgamated mixture of metal that includes copper. e. a and d only Ans: c 3. Archimedes was able to measure the density of the King’s gold crown by a. finding the philosopher’s stone. b. taking a measuring tape and measuring its volume. c. weighing it underwater. d. weighing it on his own special, unusually accurate scale. e. weighing it, and then measuring how much water it displaced when placed in water. Ans: e 4. What is the volume of a gold nugget that weighs 100 grams if the density of gold is 19.3 grams per cubic centimeter? a. 5.2 cc b. 14.6 cc c. 16.2 cc d. 0.19 cc e. 1930 cc Ans: a

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An unknown piece of metal weighing 2 kg’s is found to have a volume of 0.15 cubic meters. What is its density? a. 0.30 kg/m3 b. 17.4 kg/m c. 13.3 kg/m3 d. 18.6 kg/m3 e. 33.3 kg/m3

Ans: c 6. The pressure on any particular object a. is equal to its mass times its acceleration. b. is the force on an object divided by the acceleration of the particles involved. c. is the force divided by the area over which the force is applied. d. all of the above e. a and c only Ans: c 7. The air pressure inside a rubber tire a. is caused by a vacuum inside the tire. b. is equal to the pressure on a tire gauge plus the pressure of the atmosphere outside. c. results from the kinetic energy of the air molecules inside the tire. d. results from the collisions of air molecules with the interior surface of the tire. e. b, c, and d Ans: e 8. A unit used to measure pressure is the a. pound per square inch b. Pascal c. Newton/m2 d. all of the above e. a and b only Ans: d

9. A woman with a mass of 60 kg wears shoes with high heels. The square heels measure 0.8 cm on a side. At one point during her stride, all of her weight is on one heel. What is the pressure on the floor at that point? a. 4.8 x 107 Pa b. 576,435 Pa c. 9.2 x 106 Pa d. 7544 Pa e. 4800 Pa Ans: c 10. A perfectly round stone column is 1.5 meters in diameter and 10 meters tall. If the density of the column were 4,000 kg per cubic meter, what is the approximate pressure at the bottom of the column? a. 6.4 x 107 Pa b. 6.8 x 107 Pa c. 34564 Pa d. 720,000 Pa e. 3.9 x 105 Pa Ans: e 11. Suppose you have a column of water standing as an aquarium in a restaurant. If you decided to double the height of this column of water when you remodeled your restaurant, what would happen to the pressure at the bottom of the column? a. It would stay the same since the pressures cancel out because the radius of the column is the same. b. It would increase by 9.8 m/s2, the acceleration due to gravity. c. It would quadruple. d. It would double. e. It would be half the original pressure due to the Bernoulli effect. Ans: d 12. The pressure at the bottom of a five foot deep section of Lake Michigan a. is greater than a five foot deep pool in your yard. b. is less than a five foot deep circular aquarium with a radius of 2 meters. c. is the same as any other five foot deep, static body of water. d. depends mostly on the total amount of water in the Lake. e. cannot be sure given this information Ans: c

13. What is the pressure at the bottom of a 3-meter tall column of water with a radius of 1 meter? (The density of water is 1000 kg/m3 or 1g/cc and the area of a circle is π r2.) a. 29,400 Pa b. 46000 Pa c. 22,330 Pa d. 8300 Pa e. 300 Pa Ans: a 14. The air pressure at the top of Mount Everest a. is greater than the air pressure in Paris. b. is the same as the air pressure on the Atlantic coast. c. is less than the air pressure on the California seashore. d. The answer would be different depending on the time of the year. e. There is no way to tell for sure, since the weight of the air molecules varies with altitude. Ans: c 15. The working of a hydraulic lift that raises your car up in a muffler shop so that it may be easily worked on a. depends on the immediate transmission of pressure to all parts of a fluid when the pressure is changed in one part of the fluid. b. allows the car to be raised with less work (as a physicist understands work) than would be the case without the hydraulic help. c. depends on the same principle that allows pilots to operate large wing flaps and tail rudders. d. all of the above e. a and c only Ans: e 16. A hydraulic device consists of a sealed box completely full of fluid with two piston-like plungers in it at opposite ends of the container. Plunger 1 has a much smaller diameter than plunger 2. If someone on the outside pushes plunger 1 inward through a distance of one meter, which of the following is FALSE? a. The second plunger will be pushed outward by the instantaneous transmission of pressure. b. The second plunger will be pushed out with greater force than the downward force of plunger 1.

c. This greater force from plunger 2 may be used to do work such as raising a heavy object. d. The distance that the plunger 1 moves will be less than the distance plunger two moves. e. The work done by piston 1 will equal the work done by piston two. Ans: d 17. A barometer is an instrument that measures a. relative humidity. b. atmospheric pressure. c. temperature and pressure. d. wind velocity. e. none of the above Ans: b 18. An iron ship floats when a. the weight of the water it displaces is less than the weight of the ship and its cargo. b. the weight of the water it displaces is half the weight of the ship and its cargo. c. the weight of the water it displaces is greater than the weight of the ship and its cargo. d. the weight of the water it displaces is double the weight of the ship and its cargo since the law of buoyancy has a constant of proportionality to take into account. e. None of the above; the weight of the displaced water is not relevant to whether or not the ship floats or sinks. Ans: c 19. Which of the following statements are FALSE about the buoyancy of an object? a. The force of buoyancy on a ship is equal to the weight of the water displaced by the ship and its cargo. b. Buoyancy explains why it is easier to lift an object in water than it is in air. c. An solid object with a density 60 percent that of water will have 40 percent of its total volume above the water line as it floats. d. An object only has buoyancy in liquids. e. Wood floats in water because of its buoyancy. Ans: d

20. A very light piece of wood of uniform composition floats in the water. If the density of the wood is 0.8 g/cm3, how much of the wood will be floating above the waterline? (The density of water is 1g/cm3.) a. None of it will be above the water line. The object floats with water just covering it. b. The wood will sink. c. 80 % will be above the water. d. 40 % will be above the water. e. 20 % will be above the water. Ans: e 21. The pressure exerted by a fluid on a surface a. decreases as the force exerted on the surface increases. b. decreases as the velocity of the fluid across the surface increases. c. increases as the velocity of the fluid across the surface increases. d. remains unchanged regardless of the velocity of the fluid flowing across it. e. none of the above Ans: b 22. The pressure exerted by a fluid on a surface decreases as the velocity of the fluid across the surface increases. This general principle a. is false; the pressure on a surface increases with velocity. b. accounts for the flotation of iron ships in water. c. accounts for the ability of hydraulic pressure to multiply force. d. is responsible for the lift generated by an airplane wing. e. all of the above Ans: d 23. An airplane stays in the air because a. the wing deflects air downward and Newton’s laws predict that this downward momentum change of air will produce an upward force that acts on the plane. b. the velocity of the air above the wing is slower than the velocity of the air below the wing. c. the velocity of the air moving over the wing is faster than the velocity of the air moving right below the wing. d. a and b e. a and c

Ans: e 24. The Bernoulli effect of fluid velocity on pressure a. affects the lift produced by an airplane wing. b. can help a ski jumper jump farther. c. can make a sailboat sail faster. d. all of the above e. a and b only Ans: d 25. If the temperature of a gas is held constant a. the volume decreases proportionally with decreases in pressure. b. the volume increases proportionally with increases in pressure. c. the pressure increases proportionally with decreases in volume. d. pressure and volume must remain constant regardless of any work done. e. a and b only Ans: c 26. If the temperature of an ideal gas is held constant a. the pressure must remain the same unless work is done on the system. b. the product of the pressure and the volume of the gas must remain the same. c. the volume increases proportionally with decreases in pressure. d. all of the above e. b and c only Ans: d 27. The pressure within your car tires a. will always be the same in the summer, no matter what time of day it is as long as you do not put any air in the tire or have a leak. b. will tend to be greater on a hot summer day after you have driven your car for a few hours on the hot blacktop than it would have been that morning before you got in your car. c. will be less in the afternoon after driving on the roads for a few hours than it would have been very early in the day before you started driving. d. there is not enough information to tell what the relative pressure would be under these circumstances. e. depends on the type of rubber only.

Ans: b 28. Which of the following objects has an elastic limit where the configurations of the atoms in a material change as the bonds within the material are stretched? a. a bungee cord b. your body c. a hardened steel wire d. all of the above e. a and b only Ans: d 29. What happens when the elastic limit of a material is reached and force continues to be applied? a. The material or object such as a rubber band returns to its original shape because the additional force triggers the contraction. b. The internal arrangements of atoms and chemical bonds pulls the material back to its original shape and size. c. The internal arrangements of the atoms and chemical bonds are permanently changed. d. all of the above e. a and b only Ans: c 30. When a carpenter walks across a wood beam while building a house a. the top of the beam undergoes the exact same type of interatomic force as the bottom of the beam. b. the atoms and bonds at the top of the beam are stretched apart. c. the atoms and bonds at the bottom of the beam are stretched apart. d. all of the above e. he cannot walk along the beam for very long without slipping off. Ans: c 31. Galileo a. was, among other things, a consultant to the Arsenal of Venice where people were trying to build larger ships. b. proved that the best way to increase the size of an object was to keep the same scale and proportion of the smaller object when you enlarged the

object, since this had been proven to give you the strongest structural dimensions. c. found that if you enlarge an object, the scale or proportions of the object must change to retain the strength of the original object. d. a and b e. a and c Ans: e In the 3rd century BC, Archimedes was given the task to determine if a king’s golden crown was truly pure gold. How he accomplished this is one of the best-known stories in all physics. 32. Which property of matter did Archimedes need to determine the purity of the crown? a. Density b. Elasticity c. Mass d. Pressure Ans: a 33. Archimedes needed the volume of the crown in order to calculate the quantity he needed to determine the purity of the crown. The crown had a complex shape, so the volume could not be calculated directly. What did Archimedes do? a. He divided the complex shape of the crown into very many, very small simple shapes & totaled up their volumes b. He immersed the crown in water and noticed how the level of the water changed c. He placed the crown on a balance and measured its weight Ans: b 34. Suppose the crown had a density of 19.0 g/cc (grams per cubic centimeter). Pure gold has a density of 19.3 g/cc. What should the king do about the artisan who made the crown? a. He should reward the artisan; the crown consists of pure gold b. He should reward the artisan; the crown contains even more gold than he originally commissioned from the artisan c. He should punish the artisan; the crown contains another substance besides gold d. He should not do anything; the density of the crown and the density of gold are the same according to their precision (i.e. significant figures)

Ans: c 35. Vegetable oil, water, and maple syrup have different densities and are insoluble. What happens when all three substances are placed in a beaker? (They will not undergo a chemical reaction) a. The substances mix thoroughly together b. The substances separate themselves into horizontal layers b c. The substances separate themselves into vertical columns Ans: b

1 2 The Earth consists of different substances in concentric, roughly spherically shaped regions as shown in the figure to the right. The figure is not to scale.

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36. The Earth in general is made of air, metal, rock and water. In which region of the Earth do you expect to find metal? a. 1 b. 2 c. 3 d. 4 Ans: d 37. The overall density of the Earth is 5.54 g/cc. What does this suggest about the composition of the Earth? a. The interior of the Earth consists of one element b. The interior of the Earth consists equally of two elements c. The interior of the Earth consists of several elements Ans: c 38. What does this differentiation (separation of the Earth into different layers) say about the Earth’s early history?

a. The Earth was originally entirely liquid b. The Earth was originally entirely solid c. The Earth was originally part liquid and part solid, as it is today Ans: a 39. Pumice is a specific type of rock that can float on water. What can we say about a rock of pumice? a. It must be solid rock all the way through b. It must have open spaces inside it c. It must have metal mixed in with the rock Ans: b 40. Volcanic rock can be separated into two major types, mafic (magnesium & iron rich) and felsic (silicate & water rich). Which rock is typically formed relatively close to the Earth’s surface? a. Felsic b. Mafic c. Neither Ans: a 41. You are an accident investigator. A car has crashed into a tree at high speed. The pavement shows no skid marks and there is a bit of fluid present. What can you conclude about the accident? a. The driver applied the brakes but they failed b. The driver did not apply the brakes at all c. The driver increased speed before the crash Ans: a

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A Simple Hydraulic Lift.

A hydraulic lift has an incompressible fluid completely filling the insides of the lift as shown above. At one opening (left side) is a section of relatively small cross-sectional area and at the other opening (right) is a section of relatively large cross-sectional area. 42. Suppose a force is applied straight down at the small opening as shown. What is the direction of the force at the large opening? a. Straight down b. Straight up c. Horizontal Ans: b 43. Suppose a force is applied straight down at the large opening as shown. What is the magnitude of the force at the small opening? a. More than the force at the large opening b. Less than the force at the large opening b c. The same as the force at the large opening Ans: b 44. The hydraulic lift will be used to lift a car in order to change its oil. At which end should the car be placed? a. The large opening b. The small opening c. It doesn’t matter Ans: a 45. Suppose a force is applied straight down at the small opening. How much work is done at the small end compared to the work done at the large opening? a. More work is expended at the small opening than at the large opening b. More work is expended at the large opening than at the small opening c. The amount of work is the same at both openings Ans: c 46. Incompressible fluids do not change their densities significantly under applied pressure. What else can we say about incompressible fluids in an enclosed space like a pipe or hose? a. Incompressible fluids transmit equal amounts of forces from one end of the hose to the other

b. Incompressible fluids decrease their volumes significantly as increasing amounts of pressure are applied to one end of the hose c. Incompressible fluids transmit equal amounts of pressure from one end of the hose to the other Ans: c 47. What can we conclude about the substance in a brake line that transmits force from the brake pedal to the brake pads? Consider the traffic accident again (question #10 above). a. Brake lines contain a fluid that is incompressible b. Brake lines contain air that is incompressible c. Brake lines contain a fluid that is compressible d. Brake lines contain air that is compressible Ans: a

Air Flow Approaching a Race Car 48. Many racers design their cars so that the air speed above the car is slower than the air speed below the car. Why would they do this? a. It lessens the weight of the car, allowing it to go faster b. It increases the weight of the car, giving it better traction c. It decreases the air resistance felt by the car Ans: b

A

Artesian Well Confined Aquifer

B

A Confined Aquifer with an Artesian Well A confined aquifer is a region of rock that allows ground water to flow, sandwiched between layers of rock that are impervious to water. An artesian well is simply a well that penetrates a confined aquifer. 49. Water will flow naturally up through the well if the water level inside the confined aquifer is a. As high as level A b. Anywhere between levels A and B c. Below level B Ans: b 50. Suppose the water level in the aquifer reaches up to level A. What is the pressure felt at level B (called the “hydraulic head” in geology)? a. The pressure is due only to the atmosphere b. The pressure is due only to the water in the aquifer c. The pressure is due both to the water and atmosphere Ans: c 51. Suppose the region experiences several months of drought. What will happen to the hydraulic head at the well? a. It will decrease b. It will increase c. It will stay the same Ans: a

Water in a thick section of pipe enters a thinner

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section of pipe. 52. What will happen to the speed of water as it passes from a relatively thick section of pipe to a relatively thin section of pipe? a. It will speed up b. It will slow down c. The speed won’t change Ans: a 53. The volume of water passing by per unit time is called the volume flow rate. What happens to the volume flow rate of the water as it passes from the thick section to the thin section? a. It will decrease b. It will increase c. It won’t change Ans: c 54. Nitrogen is compressible and dissolves in water when subjected to high pressures. A big danger for deep-sea divers is the bends, which occurs when divers rise too fast from deep dives. What is happening to the divers during the rise? a. Nitrogen gas is forced to dissolve into their blood and expands the blood vessels b. Nitrogen gas is forced to dissolve into their blood and shrinks the blood vessels c. Nitrogen gas that was previously dissolved into their blood expands the blood vessels d. Nitrogen gas that was previously dissolved into their blood shrinks the blood vessels Ans: c 55. One approach to alleviate the bends is to have the diver rise very slowly, to allow the change in volume of nitrogen to be gradual. Another approach is to replace nitrogen in air tanks with helium (helium is safe to breathe). What is the attraction of using helium? a. Helium doesn’t dissolve in blood at all b. Helium dissolves in blood at the same rate as nitrogen c. Helium expands and shrinks at a lesser rate than nitrogen Ans: c

Two sets of rocks with equal total volumes. Each rock at right has ¼ of the volume of the rock at left.

56. Weathering is the process of physically or chemically breaking down rock into smaller fragments. Which is more susceptible to weathering, the single rock at left or the four smaller rocks at right? a. The single rock; it exposes less total surface area than the four smaller rocks b. The four smaller rocks; they expose more total surface area than the single rock c. Weathering will be the same for both rocks Ans: b Volcanic Ridge

Continental Plate

Ocean Plate

Ocean Plate

Continental Plate

Moving magma The Earth’s surface consists of several pieces or plates of rock that are driven by the movement of magma underneath them. Magma rises from deep in the mantle, can move horizontally, and then sinks back into the mantle. 57. What can be said about the temperature of the rising magma compared to the surrounding rock in the mantle? a. The rising magma is cooler b. The rising magma is hotter c. The rising magma and other mantle rock are the same temperature Ans: b

58. The ocean plates are splitting apart where the magma begins to move horizontally. What force best describes this activity? a. Buoyancy b. Compression c. Tension d. Weight Ans: c 59. In many volcanic eruptions, steam explodes out of the top of the volcano. What happens to the temperature of the steam as it emerges from the volcano? a. The temperature of the steam decreases b. The temperature of the steam increases c. The temperature of the steam remains the same Ans: a 60. Since plates split apart at some locations on the Earth, they must come together at other locations. What might you expect to happen to the colliding plates? a. Rocks are folded and mountains are built due to compression b. Lava from the mantle spills into the ocean due to tension c. Both plates sink into the mantle due to gravity d. The plates “bounce” off of each other due to elasticity Ans: a

Crater walls Incoming Asteroid Ejected Lava Surface of Moon Crater peak An asteroid impacts the Moon and makes a crater. The crater is circular in shape with a small peak at its center. The asteroid itself is vaporized in the impact and the crater is surrounded by lava ejected from the impact site. 61. Why is there a peak at the center of the crater? a. The asteroid exerted a large compression force upon impact b. The gravity of the Moon forced the peak upward

c. The surface of the Moon behaved elastically during the impact Ans: c True or False

1. The pressure at the bottom of a column of water depends not only on the column’s height, but also on its diameter. Ans: False 2. The pressure inside a car tire depends mostly on the gravitational potential energy of the molecules inside the tire. Ans: False 3. The upward force of buoyancy that keeps a log afloat is equal to the weight of the water displaced by the log. Ans: True 4. If the temperature of a gas is held constant, the volume increases proportionally with increases in pressure. Ans: False 5. If the pressure of a gas is held constant, the volume increases proportionally to the temperature. Ans: True 6. Hooke’s law implies that if you double the force on an elastic object, you always double its length. Ans: False

7. As you walk across a wooden beam, the underside of the beam undergoes compression, which is the compression of the beams interatomic bonds in this location. Ans: False 8. It is well known by physicists that if you want to double the size of any object, the best way to maintain its strength is to keep the same proportions in terms of size and length; in other words double every measurement for maximum strength in this case. Ans: False 9. The pressure inside a bicycle tire is due to the collisions that the air molecules inside make with the tire walls. Ans: True 10. Liquid crystals become more ordered when electricity is passed through them. Ans: True