Physics Test 2
A 1-N balloon is suspended in air, drifting neither up now down. (a) How much buoyant force acts on it? (b) What happens if the buoyant force decreases? (c) What happens if it increases?
(a) 1 N up (b) it falls (c) it rises
The temperature of absolute zero is stated as ______________.
-273°C
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 displaces, 5 N buoyant force
A 1 kg balloon at equilibrium in the air is buoyed up with a force of __________.
10 newtons
If an object submerged in water displaces 10 kg of water, the buoyant force on the submerges object is _____________.
100 N
What is the mass density of water? What is water's normal weight density?
1000 kg/m³; 9800 N/m³
If a suspended 1-kg object stretches a spring by 4 cm, how much will the spring be stretched when it supports a 3-kg object?
12 cm
Which one of these values is the lowest temperature?
270 K
A brass cube has a mass of 4 kg. What is the mass if a brass cube twice as tall and twice as wide?
32 kg
If the linear dimensions of an object are doubled, by how much does the surface area increase? By how much does the volume increase?
4 times, 8 times
At what height is half of the mass of air below the atmosphere?
5.6 km
What do you get if you rotate an arch through a complete circle?
A dome
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
What is the purpose of a model in science?
A model is an abstraction that helps us visualize and predict
How does a plasma differ from a gas?
A plasma is made up of ionized atoms
Distinguish between adhesive and cohesive forces.
Adhesive forces are between unlike substances, whereas cohesive forces are between like substances
Who first explained Brownian motion and made a convincing case for the existence of atoms?
Albert Einstein
How does an ideal gas differ from ordinary air?
An ideal as is one where the disturbing effects of forces between molecules and the finite size of molecules can be ignored
The periodic table of the elements is a list of ________________.
Atoms
Why can atoms not be seen with a powerful optical microscope?
Atoms are much smaller than a wavelength of light
In terms of atom arrangements, distinguish between crystalline and noncrystalline substances.
Atoms in crystals are in an ordered array. In amorphous materials, they are randomly distributed
Atmospheric pressure decreases with increasing ______________-.
Attitude
Why does the air exert a buoyant force on all objects in air, not only light objects such as balloons?
Because of Archimedes' principle
The name given to the shape of a sagging rope supported at its ends is a _____________.
Catenary
How does close packing of iridium atoms affect the density of iridium?
Close packing of iridium atoms accounts for its great density
Is it tension or compression that strengthens an arch that supports a load?
Compression
The operation of a hydraulic press best illustrates ____________.
Conservation of energy
Rank the following scientific discoveries from first to last:
Discovery of Brownian motion; Discovery of the atom; Discovery of the electron
The pressure increases on a block resting on a table when you increase the _______________.
Downward force on the block
What kind of attraction pulls electrons close to the atomic nucleus?
Electric
What type of force holds atoms together in a crystal?
Electric
Does Hooke's law apply to spring compressions, or only stretches?
For both spring compressions and stretches
Why is there no horizontal buoyant force on a submerged object?
Force vectors on the sides cancel one another
When you use an I-beam in a horizontal application, the region between the flanges is _____________.
Free of stress
Cite the temperatures for freezing water on the Celsius and Fahrenheit scales. Cite the same for boiling water.
Freezing: 0°C. 32°F; boiling: 100°C, 212°F
In which direction does internal energy naturally flow between hot and cold objects?
From high temperature to low temperature
Which of these atoms has the largest number of neutrons in the nucleus?
Gold
What is the evidence that dark matter exists?
Gravitational forces within galaxies are too great to be accounted for with ordinary matter
What keeps the atmosphere around our planet?
Gravity
Water pressure in lake is __________________.
Greater at the bottom
What is the most abundant element in the known universe?
Hydrogen
Which of the following is an element?
Hydrogen
A scuba diver is planning to dive to the same depth in the open ocean and in a deep lake. Considering that salt water is denser that fresh water, where would the diver feel more pressure?
In the ocean
A strong wind blows over the house shown in the figure. The wind is much stronger over the house's roof than lower down, and the house has an open chimney. A window on the ground floor is open, and so are the doors inside the house. Which way will air flow through the house?
In the window and out the chimney
Does a hot object contain internal energy or does it contain heat? Or do the two terms mean the same thing?
Internal energy. They are not two terms for the same thing
A gas will become plasma when it ____________.
Is electrically charged
What happens to air pressure inside a balloon when it is squeezed to half its volume?
It doubles
What happens to the density f air in a party balloon when it is squeezed to half its volume?
It doubles
If you punch holes in the side of a container filled with water, in what direction does the water initially flow outward from the container?
It flows straight out, perpendicular to the wall
How does one isotope differ from another?
It has a different number of neutrons
How does the electric charge of an electron compare with the electric charge of a proton?
It is equal and opposite
A loaded ship arrives at the first freshwater lock of the Panama Canal, will it float higher or lower than in the open ocean?
It will float lower
Who advanced the idea of atoms in the early 1800s?
John Dalton
The temperature scale favored by scientists is _______________.
Kelvin
What is meant by "translational" kinetic energy?
Kinetic energy of motion that carries a molecule from one place to another
When Dr. Hewitt immerses the object in water, how does the loss of weight of the object compare with the buoyant force of the water?
Loss the weight is equal to the buoyant force
Why would a water barometer have to be 13.6 times taller than a mercury barometer?
Mercury is 13.6 times denser than water
The smallest particle of a substance that consists of two or more atoms bonded together is called ________________.
Molecule
Are most of the atoms around us younger or older than the Sun?
Most are older than the Sun
How are elements with nuclei heavier than hydrogen and helium formed?
Nuclear fusion in stars
Do we see atoms directly or only indirectly with a scanning electron microscope?
Only indirectly
Dark matter is considered to be __________.
Plentiful in the universe
Is pressure greater of less in regions where streamlines are crowded?
Pressure is lower where streamlines are closer
A stone of volume V submerged in water displaces the _________.
Same volume of water
An object denser than water will ____ in water. An object less dense than water will ________ in water. An object with the same density as water will _________ in water.
Sink, float, neither sink nor float
What geometrical shape has the least surface area for a given volume?
Sphere
Why were multiple vertical columns needed to support the roofs of stone buildings in ancient Egypt and Greece.
Stone breaks under tension
What is Hooke's law? Does it apply to elastic materials or to inelastic materials?
Stretch is proportional to force for elastic materials
A column of mercury 76 cm tall has a weight that is equal to ________________.
That of a column of water 10.3 m tall
Why are high-altitude research balloons only partially inflated when launched?
The atmospheric pressure decreases as they rise, so they expand. If they were fully inflated at launch, they would burst at high altitudes
When you drink liquid through a straw, is it more accurate to say the liquid is pushed up the straw rather than sucked up the straw? What exactly does the pushing?
The atmospheric pressure outside the straw pushes the liquid toward the lower pressure in your mouth
Why do the gondolas of the Falkirk Wheel the same weight whether or not they carry boats?
The boats displace water out of the gondolas equal to their weights
What happens when Dr. Hewitt places a card on a glass full of colored water and it turns it upside down?
The card stays, and the water also stays in the glass
Does the strength of a person's arm depend more on its length or its cross-sectional area?
The cross-sectional area
The large piston of a hydraulic lift has an area twice the area of the small piston. In comparison to a force applied on the small piston, what would the force exerted by the large piston be?
The large piston would have double the force
Why are heavier elements not mich larger than lighter elements?
The larger positive charge in the nucleus pulls the electrons into closer orbit
What is at the center of every atom?
The nucleus as protons and neutrons
What happens to the pressure in all parts of a confined fluid if pressure in one part is increased?
The pressure everywhere increases by the same amount
The narrower pipes in your home are those feeding your faucets and showers. Compared to the water pressure in the large pipes running to your home, what would the internal pressure of the water flowing through the small pipes be?
The pressure in the small pipes would be the lowest because water moves there at the highest speed
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 because saltwater is more dense
How does water pressure 2m below the surface of a small pond compare with water pressure 2m below the surface of a huge lake?
The pressure will be the same
Compared with the energy it takes to separate oxygen and hydrogen from water, how much energy is released when the recombine?
The same amount of energy is released when they recombine
How does faster-moving air above an airplane wing affect the pressure on the wing?
The speed increases as the air flows over the wing, so the pressure decreases
Why are vertical columns not needed to support the middle of domed stadiums, such as the Jefferson Memorial?
The weigh produces compression that supports the dome.
The caissons of the Falkirk Wheel are balanced only when __________.
Their water levels are the same
What occurs when a proton and an antiproton meet?
They annihilate each other
The number of atoms in a common water molecule is _____________________.
Three
Why do climbers need to bring along oxygen when conquering Mount Everest?
To breathe because the atmosphere is less dense than at sea level
Why are the cross-sections of metal beams in the shape of the letter I instead of solid rectangles?
To reduce the weight of the beam while preserving the resistance to bending
Which form of energy determines temperature: translational kinetic energy, rotational kinetic energy, vibrational kinetic energy, or all of these?
Translational only
According to Hooke's law, if you double the force when stretching a spring, the elongation of the spring is normally __________________.
Twice as much
With respect to volume, mass, and density, which changes when you squeeze a loaf of bread? What doesn't change?
Volume decreases, mass stays the same, density increases
Atmospheric pressure is mainly due to the _________________.
Weight of air
Why is a blob of bread dough said to be inelastic?
When deformed, it does not return to its original shape
Why is a metal spring said to be elastic?
When deformed, it returns to its original shape
The mass of an atom is _______________.
concentrated in the atomic nucleus
When a tree branch is bent, the region in the center of the branch is the ___________.
neutral layer
There is a condition in which the buoyant force on an object does equal the weight of the object. What is this condition?
the object is neutrally buoyant, so it will neither sink nor float
Atoms in a crystalline state or in an amorphous state are
vibrating about their own positions
