Physics Exam 2
Which of the following physical quantities should be conserved for an isolated system?
All of them. Linear Momentum. Mass. Angular Momentum. Energy.
A watt is equl to
1 J/s.
A person runs up a long flight of stairs in 10 seconds. If the person's weight is 600 N and the vertical height of the stairs is 20 meters, the person's power out put is
1,200 W.
The cabin pressure of a passenger jet cruising at high altitude (30,000 ft) is about 10.29 psi greater than the pressure outside. What is the outward force on a window measuring 1 foot by 1 foot? Conversion factor: 1 ft = 12 inches.
1,481.8 lb.
A 4.0-kg block travels around a 0.50-m radius circle with a velocity of 6 m/s. Its angular momentum is
12.
When a 4-cubic foot block of wood floats in a fluid whose weight density (DW) is 60 lbs per cubic foot. 3/4 of the block's volume is submerged or immersed in the liquid. The buoyant force on the block is
180 lbs.
The gauge pressure of the water in a swimming pool at 10 ft is ____________________________the gauge pressure of the water at 5 ft
2 times
A water tank is 3 meters wide, 3 meters long and 3 meters deep. How much water in kg will it hold if the mass density of water (D) is 1000 kg/m3?
27,000 kg.
A railroad car with amass of 20,000 kg rolls into a second stationary car with a mass of 40,000 kg. The cars latch together and move off with a speed of 1.2 m/s. How fast the first car moving before the collision?
3.6 m/s
A kid slides down an icy (frictionless) hill starting from rest. At the top, his gravitational potential energy is 500 J. He slides part way down the hill to a point where his gravitational potential energy is 200 J. His kinetic energy at that point will be
300 J.
Continuation of the previous question (Question #3). The pressure on A2 is
4 psi
Two pistons push down on the fluid filling two cylinders connected by a narrow hose, as shown in the figure below. The area A1 is 1 square inch, and the area A2 is 10 square inches. A force of 4 pounds is exerted downward on piston, as shown below. The pressure on A1 is
4 psi
Continuation of the previous questions ((Question #3 and #4). The force F2 needed to keep piston 2 in place is
40 lbs
Continuation of the previous questions: At the bottom of the dam, the speed of the moving water is
44.3 m/s.
A large chunk of a metal has a mass of 393 kg and its volume is measured to be 0.05 m3. The metal's mass density (D) is
7860 k g m 3.
The mass of 1 cubic meter of fresh water is 1,000 kg. At the top of a 100 m hydroelectric dam the potential energy of the cubic meter of water is
980000 J.
In baseball game, catchers use a thick and padded mitt to catch 90 mph fast balls. When the ball is caught, it momentum becomes zero. The catchers' hand don't get hurt, though they catch a 90 mph fast ball, how?
A small force is applied over a long time to bring the baseball's momentum to zero.
Which statement is always true about an inelastic collision?
Linear momentum is conserved, kinetic energy is not conserved.
Three students determine the gravitational potential energy of an object at a given location. Student A says the gravitational potential energy is positive in value, student B says it is zero in value, and student C says it is negative in value. Which of these students can be correct?
All of the students
A scientist analyzes the properties of a sample of matter and finds it conforms to the shape of its container. In which of the phases could this sample exist?
Any phase except the solid phase.
The upward force that keeps a ship afloat is an example of application of
Archimedes's principle.
A shower curtain moves to shower head when water flowing from the shower head. It is an example of
Bernoulli's principle.
Two electric motors, A and B are used to do work. The power of motor A is twice that of motor B. Which of the following statements is/are true?
Both - motor A can do twice as much work as motor B in the same amount of time, and motor A can do the same amount of work as motor B in half the amount of time.
When two or more elements or molecules are combined chemically, they form a(an)
Compound
Weight density (DW) is
D x g
The upward force experienced by an object or a substance immersed partly or completely in a liquid can be mathematically written as
F B = D W ( l i q u i d ) × V ( l i q u i d )
Work done is defined as
F x d
The alternate form of Newton's II law is
F= delta P/ delta T
A student first dives off a platform 5.0 m above the water. Next she dives off a platform 10.0 m above the water. How does her kinetic energy (just as she strikes the water) compare in each dive?
Her kinetic energy is twice as much in the second dive.
Water is flowing through a pipe whose cross-sectional area at point A is larger than the cross-sectional area at point B. The reading on a pressure gauge connected to the pipe at point A will be ____________________ the reading on a pressure gauge connected to the pipe at point B.
Higher than
You, an astronaut, ventured out of the international space station to check the solar panel. You are tethered to the space station and floating. Suddenly the tether is snapped. You need to get to the emergency door in the space station, which is located 5 feet behind you. Your space suit does not have any jet pack. You have a hammer in your hand and how would you use it to reach the emergency door behind you?
I will throw the hammer forward so that I can move backward to reach the emergency door.
How can a satellite in orbit about the Earth increase its linear momentum, but keep its angular momentum constant?
Increase its speed of orbit and decrease its radius of orbit.
A student inhales to fill her lungs with air, thereby slightly increasing the volume of her body. What effect does this have on the density of her body?
It decreases the density.
A scientist determined some of the elements found in a sample of sea water. One of these elements contains one proton in its nucleus, which makes it the element Hydrogen. A second element was found to contain one proton in its nucleus, but also one neutron. What can be said about this second element?
It is also Hydrogen.
The unit for work is
Kilowatt-hour, Joule, N.m
If a force on an object is aimed in the opposite direction of the object's motion (F and d are anti-parallel or opposite), force does
Negative work
Two inflated balloons are of identical size and shape, but one filled with hydrogen, the other with helium. Which has the larger buoyant force on it?
Neither - the buoyant forces must be equal because the it depends only on the volume of air dislaced.
A box fell from a moving truck and quickly skidded to a stop. While the box was moving it had kinetic energy, but when it stopped its kinetic energy was zero. Is this a violation of the law of conservation of energy?
No, because all the kinetic energy of the box was converted to other types of energy.
A student attempted to push his stalled car by exerting a force of 1000 N on it, but was unable to move the car. Did the student do work on the car in this case (in physics sense)?
No.
What type of reactions can affect the identity of an atom?
Nuclear reactions.
The hydraulic lifts and braking systems are examples of application of
Pascal's principle.
If a force on an object is aimed in the same direction as the object's motion (F and d are parallel), force does
Positive work
A barrel is being lifted, in one case, it is lifted directly up to the top and in another case, it is rolled across a ramp to the top. What can you about the work done in both cases?
Same amount of work is done in both cases.
When air blows past a chimney the speed of the air increases as it goes over the top of the chimney. What effect does this have on the air pressure just above the chimney?
The air pressure above the chimney is decreased.
A hydrometer determines the alcohol content of wine by measuring its density. When placed in wine sample A the hydrometer floats higher in the wine than it does when placed in wine sample B. How does the density of sample A compare to that of sample B?
The density of sample A is greater than that of sample B.
Which of the following is NOT an example of potential energy?
The energy of a body moving across a horizontal surface.
Two boxes, A and B are lifted above the floor. The mass of box A is twice that of box B, but box B is lifted to a height twice that of box A. How does the gravitational potential energy of each box compare?
The gravitational potential energy of both boxes is equal.
A car and a truck are traveling in the same direction along a road. The truck has twice the mass of the car, but the car has twice the velocity of the truck. How does the magnitude of the kinetic energy of each vehicle compare?
The kinetic energy of the car is twice that of the truck.
A car and truck are traveling with the same speed along a road. If the truck's mass is twice that of the car, how do their kinetic energies compare?
The kinetic energy of the truck is twice that of the car.
Two football players run toward each other and collide. The large player was running slowly, while the small player was running quickly just before the collision. Upon colliding they stuck together and immediately 'stopped in their tracks'. How did the magnitudes of the linear momentum of each player compare before the collision?
The linear momentum of both players was equal.
A car and a truck are traveling in the same direction along a road. The truck has twice the mass of the car, but the car has twice the velocity of the truck. How does the magnitude of the linear momentum of each vehicle compare?
The linear momentum of both vehicles is equal.
Liquid mercury has a density much greater than that of water. If equal volumes of mercury and water are measured, how will their masses compare?
The mass of the mercury will be greater than the mass of the water.
If the area of the larger piston is five times that of the smaller piston, how does the pressure in each cylinder compare?
The pressure in the smaller cylinder is equal to the pressure in the larger cylinder.
Why can a person lie on a bed of nails and not be injured, yet she/he is seriously injured by stepping on a single nail?
The pressure is smaller on the bed of nails than on the single nail.
Given that the density of oil is less than that of water, how would the graph of pressure versus depth for oil compare to that for water?
The pressure versus depth graph for oil will have a smaller slope than the graph for water.
The pressure in a container of water increases with the depth below the water's surface. What happens to the pressure if the container is taken to another planet, where the acceleration due to gravity is different than the acceleration due to gravity on Earth?
The pressure will still increase with depth below the surface.
Two students jump into a swimming pool. Student A floats easily, while student B sinks rapidly in the water. Which statement is true?
The specific gravity of student A is less than that of student B.
What does it mean for a physical quantity in an isolated system to be conserved?
The total amount of it in the system stays constant.
After an inelastic collision of two balls, the total kinetic energy of the two balls is measured to be 36 J. What can be said about the total kinetic energy of two balls before the collision?
The total kinteci energy of the two balls was more than 36 J.
Consider a situation in which a tennis ball is hold on the ground and you tell your friend that the tennis ball has negative gravitational potential energy. What do you mean by that?
Work is required to be done on the tennis ball to raise it from the hole to the ground.
Momentum is
a vector quantity.
Fluid pressure depends on
all of the given options. gravitational acceleration. the fluid's density the depth of the fluid.
The brakes on a car do work on the car to slow it down. The work done on the car by the brakes is
always negative in value.
Substances which are solid but do not have a regular structure are called
amorphous solids.
A plasma state of matter is
an ionized gas (soup of charged particles).
The pressure exerted by a gas is the result of
atomic and molecular collisions.
In a crystalline solid,
attractive forces between atoms. or molecules are very strong atoms or molecules are rigidly bound to their neighbors. Correct! all of the given options. atoms or molecules are arranged in a regular, geometric pattern.
A device that measures the atmospheric pressure is called a
barometer
If air resistance and other types of friction can be ignored, the gravitational potential energy of a falling object will
be converted into kinetic energy.
The energy of a ball rolling up an inclined plan is
both kinetic and potential.
An object moving in a circle has
both linear and angular momentum.
The upward force exerted by a fluid on an object or a substance partly or completely immersed in it is called
buoyant force.
Impulse is defined as
change in momentum
The molecule is the basic unit of all
compounds.
As you go higher up in altitude, the atmospheric pressure
decreases
If an object's height is halved, compared to its initial height from the ground, its gravitational potential energy
decreases by a factor of half.
The upward force experienced by an object or a substance partly of completely immersed in a fluid
depends on both the density of the fluit and the object or the substance.
For an object immersed in a fluid the fluid pressure causes a force that
pushes inwards on all surfaces of the object
To be able to do work, a system must have
energy
The Law of Conservation of Energy states that
energy can be transformed from one form to another. energy can't be created or destroyed. Correct! all of the given options. the total energy of an isolated system is constant.
A sealed box contains air under pressure. The outward pressure on the walls is
equal on all walls
When an object or substance floats in a liquid, the buoyant force experience by the object is ____________________the weight of the object.
equal to
You press a push pin that has a varying cross-sectional area between the palms of your hands. The area of the push pin pushing against your left palm is twice the area of the push pin pushing against your right palm. The force on your left palm is _______________ the force of your right palm.
equal to
Suppose after reaching the bottom he then continues sliding up another icy slope on the other side of the valley. When he finally comes to a stop he will have reached a height
equal to the height he started from on the other hill.
The difference between the pressure inside and outside a tire is called
gauge pressure.
Decreasing the volume of a gas contained leads to
increase in collisions. decrease in separtaion between atoms and molecules. increase in pressure. Correct! all of the given options.
If the outside air pressure decreases, the reading on a tire gauge connected to a tire
increases
When the temperature increases, the pressure
increases
When the velocity of an object is doubled, its kinetic energy
increases by a factor of 4.
Consider a situation where two moving objects collide, stick to each other and move off together. Kinetic energy before and after collision
is definitely not conserved.
Consider a situation where a skater pulls her arms inward, causing her rotation rate to speed up. Angular momentum in this case
is defnitely conserved.
Consider a situation where two moving objects collide, stick to each other, and move off together. Linear momentum of the system
is defnitely conserved.
For a flat tire, the pressure inside the tire
is equal to the pressure outside the tire.
When an object sinks in a liquid, the volume of the displaced fluid
is equal to the volume of the object.
Power generated by car
is partally lost due to friction.
The unit for angular momentum is
kgm^2/s
When an object is moving in a straight line on a level ground, it has
kinetic energy
For a free body oscillating up and down at the end of a spring, the energy is
kinetic energy. elastic potential energy. gravitational potential energy. Correct! all of the above.
Concrete shoes, skimboards and snow shoes are designed to distribute a person's weight over
large area.
Consider weighing an object or substance in air and partly immersed in a fluid. The weight of the object or the substance, when it is partly immersed in the liquid, would be
less than the weight of the object or the substance in the air.
The total momentum, P, of the system in the figure below is
m1v1-m2v2
Change in temperature and pressure causes significant changes to mass density (D) of gases because
majority of volume between gas atoms and molecules is empty and can be compressed.
The column height of any liquid that corresponds to the atmospheric pressure depends on
mass density of the liquid.
Substances that are composed of two or more different compounds that are physically mixed together are called
mixtures and solutions.
Whether a collision is elastic or inelastic,
momentum is always conserved.
If a force on an object is aimed in a direction perpendicular to the object's motion (F and d are perpendicular), force does
no work
Linear momentum is defined as
p = m × v
The first rule "ideal gas laws" states that at a constant temperature
p × V = c o n s t a n t.
Pressure is the force per unit area for a force acting
perpendicular to a surface.
The unit of pressure is
pounds per square inch or psi (l b i n 2). Correct! all fo the given options. Pascal. N m 2
The nucleus of an atom consists of
protons and neutrons
In the Example 3.8 of the lecture, a man was about to jump off Horseshoe falls. Before he jumped off, his total energy is
purely gravitatinal potential energy.
In the Example 3.8 of the lecture, a man was about to jump off Horseshoe falls. When the man was about to hit water, his total energy is
purely kinetic energy.
A baseball is thrown upwards and falls back down again. If air resistance and other types of friction can be ignored, the sum of its gravitational potential energy and kinetic energy will
remain constant on the way up, and remain constant on the way down.
An object's angular momentum is characteristic of its
rotational motion
The Law of Conservation of Momentum is useful in collisions because
sytem's momenum before collision is equal to system's momentum after collision.
When a car tire is flat
the absolute pressure inside the tire is equal to the absolute pressure outside.
Pascal Principle states that in an enclosed fluid,
the applied pressure is transmitted equally to all parts of the fluid and the walls of the container.
When people get into a small boat, it settles lower (or rides lower) in the water than when there were no people on the boat and
the buoyant force increases as resulat of more water being displaced.
More concrete is needed at the bottom of a dam compared to the top of the dam because
the fluid pressure is higher at the bottom compared to the top.
The absolute pressure depends on
the gauge pressure and the atmospheric pressure.
In an atom, the number of protons is equal to
the number of electrons.
The identity for an atom is given by
the number of protons the atom has.
For a steadily flowing liquid, pressure represents the
the potential energy of the fluid.
Bernoulli"s principle states that for a fluid undergoing steady flow,
the pressure is lower where the fluid is faster.
Power is
the rate at which work is done.
Mass density (D) is defined as
the ratio of the mass to the volume of a substance.
Fluid pressure is defined as
the ratio of the weight of liquid column to the area of liquid column.
Weight density (DW) is defined as
the ratio of the weight to the volume of a substance.
The ratio of mass density (D) of a material to mass density (D) of water or the ratio weight density (DW) of a material to weight density (DW) of water is
the specific gravity.
Total energy of a system (E) is
the sum of kinetic and potential energies..
An elastic collision is one in which
the total kinetic energy remains constant.
The Law of Conservation of Momentum states that
the total linear momentum of a sytem is constant when there is no external force.
The linear momentum of a truck will be greater than that of a bus if
the truck's mass is larger than the bus's but its speed is the same as the bus. the truck's mass and speed are both larger than the bus's. the truck's speed is larger than the bus's but its mass is the same as the bus. Correct! any one of the given options.
Conservation angular momentum for an isolated system states that when the radius of the circular motion of object decreases,
the velocity of object increases.
Archimedes Principle states that upward force experienced by an object or a substance in a fluid at rest is equal
the weight of the fluid displaced by the object or substance.
Isolated system is called so because
there are no external influences
For a given force, the pressure increases
when the area decreases.
If a force on an object is aimed in the opposite direction of the object's motion (F and d are anti-parallel or opposite), the object's speed
will decrease
If a force on an object is aimed in the same direction as the object's motion (F and d are parallel), the object's speed
will increase
If the volume of a sample is doubled, its mass density (D)
will remain the same.
If you are spinning in a chair and then you spread your arms out wide, you should expect
your rotation rate to slow.