Chapter 13: Liquids

In lab you find that a 1-kg rock suspended above water weighs 10 N . When the rock is suspended beneath the surface of the water, the scale reads 8.0 N . What is the buoyant force on the rock?

2 N

How much force is needed to hold a nearly weightless but rigid 1-L carton beneath the surface of water?

9.8 N

If an object suspended by a scale shows a weight of 3 N in air, and 2 N when submerged in water, the buoyant force on the submerged object is A) 1 N B) 2 N C) more than 3 N D) 3 N

A) 1 N

What is the weight of water displaced by a 100-ton floating ship? A) 100 tons B) more than 100 tons C) depends on the ship's shape D) 100 cubic meters E) less than 100 tons

A) 100 tons

What is the cause of surface tension? A) Molecular attraction B) The temperature of the water C) Molecular repulsion D) An oil film

A) Molecular attraction

How does pressure relate to force? A) Pressure is force per unit area. B) Pressure is force per unit length. C) Pressure is the same as force. D) Force is pressure per unit area.

A) Pressure is force per unit area.

What is the relationship between liquid pressure and the depth of a liquid? Between liquid pressure and weight density? A) Pressure is proportional to both depth and weight density. B) Pressure is inversely proportional to both depth and weight density. C) Pressure is proportional to depth and inversely proportional to weight density. D) Pressure is inversely proportional to depth and proportional to weight density.

A) Pressure is proportional to both depth and weight density.

What will these objects do in water: an object denser than water, an object less dense than water, an object that has the same density as water. A) Sink, float, neither float nor sink B) Float, sink, neither float nor sink C) Sink, float, sink D) Float, sink, float

A) Sink, float, neither float nor sink

Suppose you increase the depth of the object WITHOUT changing its height. What will happen to the force due to pressure on the bottom of the object? A) The force due to pressure on the bottom of the object will increase. B) The force due to pressure on the bottom of the object will stay the same. C) The force due to pressure on the bottom of the object will decrease.

A) The force due to pressure on the bottom of the object will increase.

Suppose you increase the height of an object WITHOUT changing its depth under water. What will happen to the force due to pressure on the bottom of the object? A) The force due to pressure on the bottom of the object will increase. B) The force due to pressure on the bottom of the object will decrease. C) The force due to pressure on the bottom of the object will stay the same.

A) The force due to pressure on the bottom of the object will increase.

Suppose you increase the height of an object WITHOUT changing its depth under water. What will happen to the net buoyant force? A) The net buoyant force will increase. B) The net buoyant force stays the same. C) The net buoyant force will decrease.

A) The net buoyant force will increase.

Suppose you increase the depth of the object WITHOUT changing its height. What will happen to the net buoyant force? A) The net buoyant force will stay the same. B) The net buoyant force will increase. C) The net buoyant force will decrease.

A) The net buoyant force will stay the same.

What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased? A) The pressure everywhere increases by the same amount. B) The pressure in the other parts remains the same. C) The pressure everywhere increases by different amounts depending on the area of each part. D) The pressure everywhere decreases to conserve total pressure.

A) The pressure everywhere increases by the same amount.

How does the volume of a completely submerged object compare with the volume of water displaced? A) The volumes are equal. B) The volumes of both add to zero. C) The volume of the submerged object is less than the volume of displaced water. D) The volume of the submerged object is greater than the volume of displaced water.

A) The volumes are equal.

When you float in fresh water, the buoyant force that acts on you is equal to your weight. When you float higher in the denser water of the Dead Sea, the buoyant force that acts on you is A) equal to your weight. B) less than your weight. C) greater than your weight.

A) equal to your weight.

When a boat sails from fresh water to salt water, the boat will float A) higher in the water. B) lower in the water. C) at the same water level.

A) higher in the water.

If you float a piece of wood in a container half-full of water that rests on a weighing scale, the weight reading on the scale will A) increase. B) remain unchanged. D) decrease.

A) increase.

The volume of water displaced by a floating 20-ton boat A) is the volume of 20 tons of water. B) depends on the shape of the ship's hull. C) is 20 cubic meters. D) is the volume of the boat. E) none of the above

A) is the volume of 20 tons of water.

Compared to an empty ship, the same ship loaded with Styrofoam will float A) lower in the water. B) higher in the water. C) at the same level in the water.

A) lower in the water.

Buoyant force acts upward on a submerged object because A) pressure against its bottom is greater than pressure against its top. B) the weight of fluid displaced reacts with an upward force. C) it acts in a direction to oppose gravity. D) none of the above

A) pressure against its bottom is greater than pressure against its top.

If you float a piece of wood in a container brim-full of water that rests on a weighing scale, some water will spill. Then the weight reading on the scale will A) remain unchanged. B) increase. C) decrease.

A) remain unchanged.

The pressure at the bottom of a jug filled with water does NOT depend on A) surface area of the water. B) water density. C) the height of the liquid. D) the acceleration due to gravity. E) none of the above

A) surface area of the water.

A block of aluminum with a volume of 10 cm^3 is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 10-cm^3 block of lead. Does the lead displace more, less, or the same amount of water? A) the same amount B) more C) less

A) the same amount

When you stand with only one of your feet on a weighing scale, the scale reading is A) the same as with both feet. B) half. C) doubled. D) none of the above

A) the same as with both feet.

Buoyant force is greater on a submerged A) is the same on each B) 1-kg block of aluminum. C) 1-kg block of lead.

B) 1-kg block of aluminum.

The buoyant force acting on a 10-ton ship floating in the ocean is A) less than 10 tons. B) 10 tons. C) depends on density of sea water D) more than 10 tons.

B) 10 tons.

A scale from which a rock is suspended reads 5 N when the rock is out of water and 3 N when the rock is submerged. Buoyant force on the rock is A) 5 N. B) 2 N. C) 3 N. D) 4 N.

B) 2 N.

How is the density of a fish controlled? How is the density of a submarine controlled? A) A fish changes its weight, whereas a submarine changes its volume. B) A fish changes its volume, whereas a submarine changes its weight. C) A fish changes its weight, whereas a submarine changes its mass. D) A fish changes its volume, and a submarine changes its volume, too.

B) A fish changes its volume, whereas a submarine changes its weight.

What is the buoyant force that acts on a submerged object equal to? A) The buoyant force is equal to the weight of the object submerged. B) The buoyant force is equal to the weight of the fluid displaced by the submerged object. C) The buoyant force is equal to both the weight of the fluid displaced and the weight of the object.

B) The buoyant force is equal to the weight of the fluid displaced by the submerged object.

How does the buoyant force on a submerged object compare with the weight of the water displaced? A) The buoyant force is greater than the weight of the water displaced. B) The buoyant force is equal to the weight of the water displaced. C) The buoyant force is less than the weight of the water displaced. D) Both are zero.

B) The buoyant force is equal to the weight of the water displaced.

What is the condition in which the buoyant force on an object does equal the weight of the object? A) It will sink. B) The object is neutrally buoyant, so it will neither sink nor float. C) It will float almost completely out of the water. D) It will float.

B) The object is neutrally buoyant, so it will neither sink nor float.

How does the water pressure 1 m below the surface of a small pond compare with the water pressure 1 m below the surface of a huge lake? A) The pressure will be less. B) The pressure will be the same. C) The pressure will be greater. D) The pressure will be zero in both cases.

B) The pressure will be the same.

The attraction between unlike substances is called A) cohesion. B) adhesion. C) depends on the substances.

B) adhesion.

Water pressure on a submerged object is greatest against its A) sides. B) bottom. C) same against all surfaces D) top. E) none of the above

B) bottom.

The attraction between like substances, stickiness, is called A) depends on the substances. B) cohesion. C) adhesion.

B) cohesion.

Surface tension is a direct result of A) adhesive forces between molecules in a liquid or solid. B) cohesive forces between molecules in a liquid. C) Archimedes' principle. D) viscosity.

B) cohesive forces between molecules in a liquid.

The concept of pressure involves both A) area and volume. B) force and area. C) force and volume.

B) force and area.

A mountain that floats on the mantle indicates that the density of the mantle is A) about the same as that of the mountain. B) greater than that of the mountain. C) less than that of the mountain. D) none of the above

B) greater than that of the mountain.

On what factors does the buoyant force acting on an object depend? A) both height of the object and depth under water B) height of the object C) depth under water

B) height of the object

A block of aluminum with a mass of 1 kg is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 1-kg block of lead. Does the lead displace more, less, or the same amount of water? A) the same amount B) less C) more

B) less

Pumice is a volcanic rock that floats, which means its density is A) more than the density of water. B) less than the density of water. C) equal to the density of water. D) need more information.

B) less than the density of water.

A lobster crawls onto a bathroom scale on the ocean floor. Its weight compared to its weight above the surface is A) the same. B) less. C) greater.

B) less.

Surface tension is caused by A) water's tendency to remain wet B) molecular attractions C) the interaction between air and a water surface D) temperature variations in liquids

B) molecular attractions

Buoyant force is greater on a submerged 1-cubic centimeter block of A) lead. B) same on each C) aluminum.

B) same on each

Compared to the density of water, the density of a fish is A) more. B) the same. C) less.

B) the same.

A hospital patient confined to bed will be less likely to develop bed sores with a A) firm mattress. B) water bed. C) soft mattress. D) none of these will help.

B) water bed.

Which will remain the same for two identical books, one lying flat and the other standing on an end? A) pressure B) weight C) both of these D) neither of these

B) weight

One liter of water has a mass of A) 14.7 grams. B) 500 grams. C) 1 kilogram. D) none of the above

C) 1 kilogram.

Is the buoyant force on a submerged object equal to the weight of the object itself or is it equal to the weight of the fluid displaced by the object? A) It is equal to both the weight of the object and the weight of the fluid displaced. B) It is equal to the weight of the object. C) It is equal to the weight of the fluid displaced. D) Neither. It is equal to the mass of the fluid displaced.

C) It is equal to the weight of the fluid displaced.

When you immerse the object in water, how does the loss of weight of the object compare with the buoyant force of the water? A) Loss of weight is less than the buoyant force. B) Loss of weight is greater than the buoyant force. C) Loss of weight is equal to the buoyant force.

C) Loss of weight is equal to the buoyant force.

What geometrical shape has the smallest surface area for a given volume? A) Cylinder B) Cube C) Sphere D) Disk

C) Sphere

How does pressure at the bottom of a body of water relate to the weight of water above each square meter of the bottom surface? A) The pressure is the weight density divided by 1 m^2. B) The pressure is the weight times the depth. C) The pressure is the weight of the water divided by 1 m^2. D) The pressure is the weight times the depth divided by 1 m^2.

C) The pressure is the weight of the water divided by 1 m^2.

When you immerse an object in water for a second time and record the water that is displaced by the object, how does the weight lost by the object compare to the weight of the water displaced? A) The weight loss of the object is less than the weight of the water displaced. B) The weight loss of the object is greater than the weight of the water displaced. C) The weight loss of the object is equal to the weight of the water displaced.

C) The weight loss of the object is equal to the weight of the water displaced.

Does the buoyant force on a submerged object depend on the volume of the object or on the weight of the object? A) Both volume and weight B) Neither volume nor weight C) Volume D) Weight

C) Volume

Water pressure in a lake is greater A) midway to the bottom B) at any point, for pressure is the same throughout C) at the bottom D) at the surface

C) at the bottom

A fish normally displaces its own A) weight of water. B) volume of water. C) both of these D) neither of these

C) both of these

An egg rests at the bottom of a bowl filled with water. When salt is slowly added to the water the egg rises and floats, from which we conclude A) salt water is denser than an egg. B) salt water is denser than fresh water. C) both of these D) neither of these

C) both of these

The pressure in a liquid depends on liquid A) depth. B) density. C) both of these D) neither of these

C) both of these

The amount of water displaced by a liter-sized block of ordinary wood floating in water is A) depends on the water density B) more than 1 liter. C) less than 1 liter. D) 1 liter. E) none of the above

C) less than 1 liter.

Two life preservers have identical volumes, but one is filled with Styrofoam while the other is filled with sand. When the two life preservers are fully submerged, the buoyant force is greater on the one filled with A) Styrofoam. B) sand. C) same on each as long as their volumes are the same

C) same on each as long as their volumes are the same

When holes are drilled through the wall of a water tower, water will spurt out with the greatest speed from the hole closest to A) the top of the tower. B) the middle of the tower. C) the bottom of the tower. D) all the same

C) the bottom of the tower.

A completely submerged object always displaces its own A) weight of fluid. B) density of fluid. C) volume of fluid. D) all of the above E) none of the above

C) volume of fluid.

If a 1-L container is immersed halfway into water, what is the volume of the water displaced? What is the buoyant force on the container? A) 0.5 L displaced, 10 N buoyant force B) 1 L displaced, 10 N buoyant force C) 10 L displaced, 1 N buoyant force D) 0.5 L displaced, 5 N buoyant force

D) 0.5 L displaced, 5 N buoyant force

What is the mass of 1 L of water? What is its weight in newtons? A) 1000 kg; 10,000 N B) 10 kg; 1 N C) 0 kg; 0 N D) 1 kg; 10 N

D) 1 kg; 10 N

How much air must a 100-ton blimp displace to float and neither rise nor sink? A) 10 tons B) Its volume of air C) 10,000 tons D) 100 tons

D) 100 tons

The mass of a cubic meter of water is A) 100 kg. B) 1 kg. C) 9800 N. D) 1000 kg. E) 10 kg.

D) 1000 kg.

Why isn't there a horizontal buoyant force on a submerged object? A) Forces on the sides are zero at every point. B) Force vectors on the top and bottom cancel one another. C) Forces on the top and bottom add and cancel gravity. D) Force vectors on the sides cancel one another.

D) Force vectors on the sides cancel one another.

Why does the buoyant force act upward on an object submerged in water? A) The pressure upward on the top is greater than the downward pressure on the deeper bottom. B) Water shields the object from gravity. C) The pressure downward on the deeper bottom is less than the upward pressure on the top. D) The pressure upward on the deeper bottom is greater than the downward pressure on the top.

D) The pressure upward on the deeper bottom is greater than the downward pressure on the top.

If you swim beneath the surface in saltwater, will the pressure be greater than in fresh water at the same depth? A) The pressure will be the same. B) The pressure will be zero. C) The pressure will be less. D) The pressure will be greater.

D) The pressure will be greater.

While standing, your blood pressure is normally greatest in your A) head. B) heart. C) same in each D) feet.

D) feet.

The reason a life jacket helps keep you afloat is A) the jacket repels water. B) the jacket has the same density as an average human. C) if you sink, the jacket sinks. D) the density of both you and the jacket together is less than your density alone. E) the jacket makes you weigh less.

D) the density of both you and the jacket together is less than your density alone.

A dam is thicker at the bottom than at the top mainly because A) it looks better. B) water is denser at deeper levels. C) surface tension exists only on the surface of liquids. D) water pressure increases with depth. E) none of the above

D) water pressure increases with depth.