PHYS 1310 (Ch. 13)

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?

0.5 L displaced, 5 N buoyant force

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 __________.

1 N.

What is the mass of 1 L of water? What is its weight in newtons?

1 kg; 10 N

One liter of water has a mass of

1 kilogram

The mass of a cubic meter of water is

1,000 kg.

Buoyant force is greater on a submerged

1-kg block of aluminum

The buoyant force acting on a 10-ton ship floating in the ocean is

10 tons

How much air must a 100-ton blimp displace to float and neither rise nor sink?

100 tons

What is the weight of water displaced by a 100-ton floating ship?

100 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

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

How is the density of a fish controlled? How is the density of a submarine controlled?

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

Why isn't there a horizontal buoyant force on a submerged object?

Force vectors on the sides cancel one another.

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?

It is equal to the weight of the fluid displaced.

What is the cause of surface tension?

Molecular attraction

How does pressure relate to force?

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?

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.

Sink, float, neither float nor sink

What geometrical shape has the smallest surface area for a given volume?

Sphere

How does the buoyant force on a submerged object compare with the weight of the water displaced?

The buoyant force is equal to the weight of the water dispalced

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?

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

Suppose you increase the height of the object WITHOUT changing its depth under water. What will happen to the force due to pressure on the bottom of the object?

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

Suppose you increase the height of the object WITHOUT changing its depth under water. What will happen to the net buoyant force?

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?

The net buoyant force will stay the same.

What is the condition in which the buoyant force on an object does equal the weight of the object?

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

What happens to the pressure in all parts of a confined fluid if the pressure in one part is increased?

The pressure everywhere increases by the same amount.

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?

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

Why does the buoyant force act upward on an object submerged in water?

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?

The pressure will be greater

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?

The pressure will be the same

How does the volume of a completely submerged object compare with the volume of water displaced?

The volumes are equal

Does the buoyant force on a submerged object depend on the volume of the object or on the weight of the object?

Volume

The attraction between unlike substances is called

adhesion

Water pressure in a lake is greater __________.

at the bottom

Water pressure on a submerged object is greatest against its

bottom

The attraction between like substances, stickiness, is called

cohesion

Surface tension is a direct result of

cohesive forces between molecules in a liquid

The pressure in a liquid depends on liquid

density depth

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

equal to your weight

While standing, your blood pressure is normally greatest in your

feet

The concept of pressure involves both

force and area

A mountain that floats on the mantle indicates that the density of the mantle is

greater than that of the mountain

On what factors does the buoyant force acting on an object depend?

height of the object

When a boat sails from fresh water to salt water, the boat will float

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

increase

The volume of water displaced by a floating 20-ton boat

is the volume of 20 tons of water

Buoyant force is greater on a submerged 1-cubic centimeter block of

lead and aluminum - same on each

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?

less

A lobster crawls onto a bathroom scale on the ocean floor. Its weight compared to its weight above the surface is

less

The amount of water displaced by a liter-sized block of ordinary wood floating in water is

less than 1 liter

Pumice is a volcanic rock that floats, which means its density is

less than the density of water

A person floats higher in the dense water of the Dead Sea because

less volume of water is displaced.

Compared to an empty ship, the same ship loaded with Styrofoam will float

lower in the water

Surface tension is caused by __________.

molecular attractions

Buoyant force acts upward on a submerged object because

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

remain unchanged

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

salt water is denser than fresh water, salt water is denser than an egg

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

same on each as long as their volumes are the same

The pressure at the bottom of a jug filled with water does NOT depend on

surface area of the water

When holes are drilled through the wall of a water tower, water will spurt out with the greatest speed from the hole closest to

the bottom of the tower

The reason a life jacket helps keep you afloat is

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

Compared to the density of water, the density of a fish is

the same

A block of aluminum with a volume of 10 cm3 is placed in a beaker of water filled to the brim. Water overflows. The same is done in another beaker with a 10-cm3 block of lead. Does the lead displace more, less, or the same amount of water?

the same amount

When you stand with only one of your feet on a weighing scale, the scale reading is

the same as with both feet

A completely submerged object always displaces its own

volume of fluid

A fish normally displaces its own

volume of water, weight of water

A hospital patient confined to bed will be less likely to develop bed sores with a

water bed

A dam is thicker at the bottom than at the top mainly because

water pressure increases with depth

Which will remain the same for two identical books, one lying flat and the other standing on an end?

weight