Physics Test 2
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 approximate mass of a column of air 1 cm2 in area that extends from sea level to the upper atmosphere? What is the weight of this amount of air? What is the pressure at the bottom?
1 kg, 10 N, 100 kPa
What is the mass of a cubic meter of air at room temperature (20°C)?
1.21 kg
Suppose that we repeat the experiment shown in the video, but we replace one of the cylinders with a cylinder that has twice the radius (and use larger containers of water). If the height of the original cylinder is hh, how deeply must we submerge the new cylinder to get the same weight reduction as in the video?
1/4 H To get the same reduction in weight, the same volume of cylinder must be submerged. The volume of a cylinder is VV= πr2hπpir2h, so if we double the radius, we must reduce the depth of immersion by a factor of four.
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 submerged object is __________.
100 N
If 1.0 gram of antimatter meets with 4.0 grams of matter, the energy released would correspond to the energy equivalent of
2 grams
A medium size apple weighs 1 NN and sits on an area of about 4 cm2cm2 (0.0004 m2m2). Determine the pressure that the apple exerts on the surface.
2,500 Pa
If the pressure in a hydraulic press is increased by an additional 10 N/cm2, how much extra load will the output piston support if its cross-sectional area is 50 cm2?
500 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.
What is the purpose of a model in science?
A model is an abstraction that helps us visualize and predict.
Atmospheric pressure decreases with increasing _________.
Altitude
What Makes an Object Float or Sink?
An object more dense than the fluid in which it is immersed will sink. An object less dense than the fluid in which it is immersed will float. An object having a density equal to the density of the fluid in which it is immersed will neither sink nor float.
The periodic table of the elements is a list of __________.
Atoms
Compare the age of the atoms in your body with the age of the atoms that were part of the dinosaurs.
Both are ageless
What are the five most common elements in humans?
C, H, O, N, and Ca
The size of an atom is mostly determined by the space occupied by its
Electrons
The buoyant force on a floating object is __________.
Equal to the object's weight
Which of these atoms has the largest number of neutrons in the nucleus?
Gold
What keeps the atmosphere around our planet?
Gravity
Water pressure in a 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
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.
What can be said about the pressure of an inflated balloon?
It is equal to the atmospheric pressure.
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
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 of 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.
Are most of the atoms around us younger or older than the Sun?
Most are older than the sun
Where did the heaviest elements originate?
Nuclear fission in supernovas
Which investigator is credited for discovering Brownian motion?
Robert Brown
Consider the video tutorial you just watched. Suppose we repeat the experiment, but this time place the divider closer to one side of the tube than to the other. How will the speed of the air on the wide and narrow sides of the divider compare? (Assume that burning has a negligible effect on the mass of the air circulating through the tube.)
The air will move faster on the narrow side.
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.
Why do the gondolas of the Falkirk Wheel (see Figure 13.19 in the textbook) have the same weight whether or not they carry boats?
The boats displace water out of the gondolas equal to their weights.
What is the buoyant force that acts on a submerged object equal to?
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?
The buoyant force is equal to the weight of the water displaced.
What happens when Dr. Hewitt takes the cans containing a small amount of hot water and dips them in cold water?
The cans get crushed.
Why do the card and water do what they do when Dr. Hewitt flips them over?
The card is held up by atmospheric pressure that balances the weight of water.
What happens when Dr. Hewitt places a card on a glass full of colored water and turns it upside down?
The card stays, and the water also stays in the glass.
If you place a Styrofoam cup on the table and a bunch of BBs move around it randomly, what will happen to the cup, and why?
The cup will move randomly in different directions because the BBs will exert unequal forces on the cup in different directions.
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.
Compared to hydrogen (atomic number 1), the helium atom (atomic number 2) has double the positive charge in the nucleus. How do you compare their relative sizes?
The helium atom is smaller than the hydrogen atom.
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
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.
How does the approximate number of atoms in the air in your lungs compare with the number of breaths of air in Earth's atmosphere?
The numbers are the about the same, 1023.
Why did the particles jiggle around?
The particles were struck by atoms, but unequally on different sides.
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.
If the volume of a confined gas is reduced 10 percent, how would the pressure of the gas change?
The pressure of the gas would increase by 10 percent.
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.
How does the volume of a completely submerged object compare with the volume of water displaced?
The volumes are equal
Why can atoms be seen with an electron beam?
The wavelength of the electrons is smaller than an atom.
When Dr. Hewitt immerses an object in water the second time and catches the water that is displaced by the object, how does the weight lost by the object compare to the weight of the water displaced?
The weight loss of the object is equal to the weight of the water displaced.
What is required such that an object can float on water?
The weight of the water displaced by the object, when completely submerged, is greater than the weight of the object.
How does the weight of mercury in a barometer compare with the weight of an equal cross-section of air from sea level to the top of the atmosphere?
They are equal.
Why do climbers need to bring along oxygen when conquering Mount Everest?
To breathe because the atmosphere is less dense than at sea level
Which of these elements has atoms of the greatest mass?
Uranium
Which of these elements has atoms with the greatest number of electrons?
Uranium
Why do the cans containing a small amount of hot water do what they do in the experiment when Dr. Hewitt immerses them?
When the cans are suddenly cooled, the pressure inside them is less than the atmospheric pressure outside.
If you add or subtract a proton to or from the nucleus of an atom, you produce
a completely different atom
It is correct to say that atoms that make up your body
a) were formed in ancient stars. b) were previously a part of your neighbor's bodies. c) are in motion at all times.
As the text cites, atoms are incredibly tiny, numerous, perpetually moving, and what else?
ageless
Who first explained Brownian motion and made a convincing case for the existence of atoms?
albert einstein
Molecules are composed of
atoms
An element is a substance consisting of
atoms of the same kind
What causes dust particles and tiny grains of soot to move with Brownian motion?
collisions with invisible molecules
The mass of an atom is __________.
concentrated in the atomic nucleus
The operation of a hydraulic press best illustrates __________.
conservation of energy
An object with a particular height is completely submerged in water. As the object is lowered within the water (away from the surface), the net buoyant force
does not change
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
The reason you don't fall between the atoms in the floor you stand on involves
electrical forces
Which of the following has the smallest mass?
electron
Which of the following are negatively charged?
electrons
An important feature of atoms is that they __________.
have wave properties
On what factors does the buoyant force acting on an object depend?
height of the object
A compound is composed of different kinds of atoms
in definite proportions
An object with a particular height is completely submerged in water. As the height of the object increases, the net buoyant force
increases.
The net force due to water pressure, exerted on a flat surface of an object submerged in the water,
is equal to the weight of the fluid displaced by the object.
A helium-filled balloon will reach its maximum altitude when __________.
its weight equals the weight of displaced air
The classic periodic table
lists the known elements
Isotopes of a given element differ in
mass number
An object having the same density as water will __________.
neither sink nor float in water
The atoms in isotopes of a particular element have different numbers of
neutrons
The atomic number of an atom is defined in terms of its number of
protons
Brownian motion has to do with the
random motions of atoms and molecules
A stone of volume V submerged in water displaces the _________.
same volume of water
Atoms combine to form molecules by way of
shared or exchanged electrons
The shell model of the atom views electrons as occupying
shells
Investigation of atoms sequenced along each horizontal row (period) of the periodic table shows that atoms decrease in
size
Compared with the wavelength of visible light, atoms are
smaller
What did Robert Brown see under the microscope?
specks of dust moving around
A column of mercury 76 cm tall has a weight that is equal to ___________.
that of a column of water 10.3 m tall
The caissons of the Falkirk Wheel are balanced only when __________.
their water levels are the same
When a party balloon is compressed to one-third its volume, gas pressure in the balloon ___________.
triples
Atmospheric pressure is mainly due to the ___________.
weight