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CONCEPTUAL PHYSICS CH13 CORRECT
DETAILED ANSWERS
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B) the same
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D) None of the above
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Two solid blocks of identical size are submerged in water
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Upon which is the buoyant force greater? CorreCt Answers -The buoyant force is the same on each block because
they displace the same volume of water
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If a fish makes itself denser, it will sink; if it makes itself less dense, it will
rise
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When the fish expands its volume, the buoyant force increases
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You'd float even higher in mercury
(density 13
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8
g/cm3)
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Should gravel be removed from or added to the barge? CorreCt Answers -? gravel should be added ?

As the automobile on a lift is being lifted, how does the change in oil level in
the reservoir compare with the distance the automobile moves? - CorreCt
Answers -The car moves up a greater distance than the oil level drops, since
the area of the piston is smaller than the surface area of the oil in the
reservoir
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what would you say? - CorreCt Answers -No, no, no!
Although a hydraulic device, like a mechanical lever, can multiply force it
always does so at the expense of distance
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No device has ever
been found that can multiply energy!

If a block of oak with 75% the density of water is placed in a bucket of
water, what percentage of the wood will be above water?
A) 75%
B) 100%, because it will float
C) 25%
D) it is impossible to tell without knowing the density of water
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- CorreCt Answers -C) 25%

All ice floats
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B) ice must always be filled with air bubbles
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D) ice expands as it sinks into water
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- CorreCt Answers A) the solid form of water is less dense than the liquid form
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B) higher in the water
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- CorreCt Answers -A) lower in the water
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B) 1 kg
C) 9800 N
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E) 100 kg
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In drinking soda or water through a straw, we make use of
A) capillary action
B) surface tension
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D) Bernoulli's principle
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About what percentage of the molecules that make up the atmosphere are
below an aircraft that flies at an altitude of 6 kilometers?
A) 40%
B) more than 50%
C) 30%
D) 50%
E) 20% - CorreCt Answers -B) more than 50
When you stand on one foot instead of two, the pressure you exert on the
floor is
A) less
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C) more
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- CorreCt Answers -C) more
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B) holds more water
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D) None of the above
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Only depth, not amount of water, contributes to pressure
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B) displacement rule
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D) All of the above
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How many forces act on a submerged body at rest in a fluid?
A) One—buoyancy
B) Two—buoyancy and the force due to gravity
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D) None of the above
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On which of these blocks submerged in water is the buoyant force greatest?
A) 1 kg of lead
B) 1 kg of aluminum
C) 1 kg of uranium
D) All the same
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B) increases
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D) None of the above
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When a fish makes itself less dense, the buoyant force on it
A) decreases
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C) remains the same
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- CorreCt Answers -B) increases
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B) increases
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D) None of the above
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When a submarine takes water into its ballast tanks, its density
A) decreases
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C) remains the same
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- CorreCt Answers -B) increases
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B) increases
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D) None of the above
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The reason a person finds it easier to float in saltwater compared with
freshwater is that in saltwater

A) the buoyant force is greater
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C) Neither of these
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- CorreCt Answers -C) Neither of these
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On a boat ride, the skipper gives you a life preserver filled with lead pellets
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A) He apparently doesn't know his physics
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- CorreCt Answers -B) He is correct
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Although the buoyant force on you will be greater, the net force
downward is greater still!

You place an object in a container that is full to the brim with water on a
scale
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How does the weight of the
object compare with the weight of the water displaced?
A) Weight of object is greater than weight of water displaced
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C) Weight of object is equal to weight of water displaced
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- CorreCt Answers -C)
Weight of object is equal to weight of water displaced
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One block is lead
and the other is aluminum
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- CorreCt Answers -C) Same
on both blocks

In a hydraulic device, it is impossible for the
A) output piston to move farther than the input piston
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C) output piston's speed to exceed the input piston's speed
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- CorreCt Answers -D) energy
output to exceed energy input
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One pascal of pressure
exerts a normal force of 1 newton per square meter
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buoyancy - CorreCt Answers -Apparent loss of weight of an object
immersed or submerged in a fluid
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Pascal's principle - CorreCt Answers -Changes in pressure at any point in
an enclosed fluid at rest are transmitted undiminished to all points in the
fluid and act in all directions
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flotation - CorreCt Answers -principle of flotation - A floating object
displaces a weight of fluid equal to its own
weight
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adhesion - CorreCt Answers -Molecular attraction between two surfaces
making contact
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Archimedes' principle - CorreCt Answers -Relationship between buoyancy
and displaced fluid: An immersed object is buoyed up by a force equal to
the weight of
the fluid it displaces
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An object with a particular height is completely submerged in water
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B) remains the same
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- CorreCt Answers -A) increases
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As the
object is lowered within the water (away from the surface), the net buoyant
force
A) decreases
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C) increases
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The net force due to water pressure, exerted on a flat surface of an object
submerged in the water,
A) is always directed perpendicular to the surface
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C) is always directed parallel to the surface
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The buoyant force on a submerged object

A) is equal to the weight of the fluid displaced by the object
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C) is equal to the weight of the object
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What is required such that an object can float on water?
A) The density of the material that the object is made out of is less than the
density of water
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- CorreCt Answers -B)
The weight of the water displaced by the object, when completely
submerged, is greater than the weight of the object
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The standard international (SI) unit of pressure, the newton per square
meter, is called the pascal (Pa)
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Science types more often use kilopascals (1 kPa = 1000 Pa)
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Does the pressure you exert on the scale change? Is there a difference in the
scale reading? - CorreCt Answers -When you shift your weight by standing
on one foot, pressure on the scale doubles
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Except for some jiggling as you shift your
weight the scale reading stays the same
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How does the displacement
method relate to the use of a kitchen measuring cup? - CorreCt Answers Put some water in the cup before you add the butter
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Then add the butter and you'll note the water
level rise
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poke it beneath the surface
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Archimedes' principle tells us that any object that displaces 10 N of liquid
will be buoyed up with 10 N
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It's only the weight of the displaced
liquid that counts
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3 kg and is
submerged in water
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So
the buoyant force on it is 10 N
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Does the buoyant force upon it increase or decrease? - CorreCt
Answers -Buoyant force remains unchanged as the boulder sinks
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%

The reason a life jacket helps you float is
A) if you sink, the jacket sinks
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C) the density of both you and the jacket together is less than your density
alone
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E) the jacket repels water
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A bubble of air released from the bottom of a lake
A) rises to the top at constant volume
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C) becomes larger as it rises
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E) none of these - CorreCt Answers -C) becomes larger as it rises
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B) depth
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B) is the same against all surfaces
C) sides of a submerged object
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- CorreCt Answers -A) bottom of a
submerged object
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B) weight of fluid
C) density of fluid
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What is the approximate mass of a 1-square-centimeter column of air that
extends from sea level to the top of the atmosphere?
A) 10 kilograms
B) 1 kilogram
C) 1 gram
D) 100 kilograms - CorreCt Answers -B) 1 kilogram



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