Physical Science Final
A food Calorie is
-equivalent to 1,000 calories. -the same thing as a kilocalorie. -a measure of the chemical energy released by the oxidation of food.
Air is a good insulator because
-gas molecules are not attached to each other. -a gas does not transfer heat very well because the molecules are far apart. -conduction takes place slowly in a gas.
A hot dog bun (volume 345 cm3) with a density of 0.14 g/cm3 is crushed in a picnic cooler into a volume of 170 cm3. What is the new density of the bun?
0.28
A loaf of bread (volume 3000 cm3)with a density of 0.50 g/cm3 is crushed in the bottom of the grocery bag into a volume of 1200 cm3. What is the density of the mashed bread?
1.25
A burn on your arm from 100°C steam is more severe than a burn from 100°C water because
100°C steam contains more energy (540 cal/g) than 100°C water.
A 2.9-kgpile of aluminum (ρ= 2.70 g/cm3) cans is melted, then cooled into a solid cube. What is the volume of the cube? Round answer to two decimal places.
1074.07
What is the mass of an 11.7 cm3 cube of seawater (density 1.03 g/cm3)?
12.1
What is the density of mercury if 29.8 cm3 has a mass of 405 g?
13.6
What volume of copper (density 8.96 g/cm3) would be needed to balance a 2.29 cm3 sample of lead (density 11.4 g/cm3) on a two-pan laboratory balance?
2.91
A bus is moving in a straight line at 20 m/s as an insect flies from the back of the bus to the front at 2 m/s. What is the speed of the insect relative to the earth's surface?
22 m/s
What is the mass of 16.3 cm3of mercury (density 13.6 g/cm3)?
222
Note that the smaller frequency is subtracted from the larger one to avoid negative beats. A tone with a frequency of 427 Hz is sounded at the same time as a 453 Hz tone. What is the beat frequency?
26 Hz
An echo is heard from a building 0.641 s after you shout "hello." How many feet away is the building if the air temperature is 22.9°C?
363 ft
What volume of iron (density 7.87 g/cm3) would be required to balance a 2.95 cm3 sample of lead (density 11.4 g/cm3) on a two-pan laboratory balance?
4.27
What is the mass of water in a 47-L, fresh-water aquarium?
47
Use g = 9.8 m/s2. A 66.2 kg student runs up a 3.00 m high stairway in a time of 3.51 seconds. How many watts of power did she develop?
554 W
Christina weighs 128 lbs. What is her mass in kilograms? What is her mass in grams?
57.9 57900
What is the mass of fresh water (ρ = 1.00 g/cm3) in a 97.0 L tank?
97.0
What is the volume when 8.80 kg of copper wires are melted, then cooled into a solid cube? [the density of copper wires is 8.96 g/cm3]
982
What gives a musical note its characteristic quality?
A combination of the fundamental frequency added to overtones.
What is an echo?
A reflected sound you hear after 0.1 s of the original.
Which of the following describes a scientific law?
A relationship between variables that is consistently observed in nature.
When does a supersonic aircraft make a sonic boom?
At all times when it is flying at the speed of sound or faster.
Ignoring friction, compare the potential energy of a book on a shelf with the kinetic energy the book will have just as it falls and hits the floor.
Both are exactly the same.
Which location would require the greatest mass if the weight of an object is the same in each place?
Earth's Moon
How do you know that it is an electric field, not electrons that move rapidly through a circuit?
Electrons in an active circuit either drift slowly, or just jiggle back and forth in one place.
Why does a balloon that has been rubbed stick to a wall for a while?
Friction transfers electrons to the balloon, which repels electrons in the wall, giving it a positive charge and opposite charges attract.
How is work related to energy?
Fundamentally, energy and work are different forms of the same thing. When you do work on something, you always give it energy. Energy is the ability to do work.
Why are the latent heat of fusion and the latent heat of vaporization said to be hidden?
Heat is absorbed or released, but a temperature change does not take place, so they are "hidden."
Is a kWh a unit of work, energy, power or more than one of these?
It is a unit of energy since energy is the ability to do work. It is a unit of work since W = Pt (from P = W/t).
Is a kWh a unit of power or a unit of work?
It is a unit of work since W = Pt (from P = W/t).
A lamp bulb is rated at 100 W. Why is a time factor not included in the rating?
It is included since a watt is a J/s.
Compare the energy needed to raise a mass 10 m on the earth to the energy needed to raise the same mass 10 m on the moon.
Less energy is needed on the moon since g is less on the moon.
A piano tuner hears three beats per second when a tuning fork and a note are sounded together and six beats per second after the string is tightened. What should the tuner do next, tighten or loosen to tune the string?
Loosen the string and hear fewer beats per second. This means the tuner is moving toward tuning the string.
An astronaut leaves a spaceship that is moving through free space. Will the spaceship move off and leave the astronaut behind?
No, both have the same relative velocity before and after leaving the spaceship.
Will a rocket on a space platform have a greater acceleration than an identical rocket firing from free space?
No, the forces are between the rocket and the exhaust gases.
Can you use a heat pump to provide the temperature difference to run a heat engine?
No, the heat supplied does not create a large enough temperature difference.
Is it possible for a transverse wave to move through air?
No, there is no force acting on the air to return it to its original position.
A spring clamp exerts a force on a stack of papers it is holding together. Is the spring clamp doing work on the papers?
No, work requires a force to move through a distance.
A 172.5 lb student runs up a stairway to a classroom 12.5 ft above ground level in 18.0 s. (a) How much work did the student do? (2160) ft·lb (b) What was the average power output in hp? (0.218)hp
SEE QUESTION
A cubic box is completely filled with 2179.0 kg of water. What is the length of one side of the box, in meters? (1.30) m Explain your reasoning. Since the density of water is (1.00) g/cm3, then the volume of 2179000 g 2179.0 kg of water is (217900) cm3. A cubic box with a volume of (217900)cm3 is (130) cm on each side. Converting (130) cm to meters, the cube is (1.30)m on each edge.
SEE QUESTION
A grasshopper floating in water generates waves at a rate of 4.0 per second with a wavelength of 8.0 cm. (a) What is the period of these waves? (0.25)s (b) What is the wave velocity? (32)cm/s
SEE QUESTION
Enter your answer in scientific notation. What is the kinetic energy of a 2700 kg car moving at 71 km/h? KE = (5. 3) × 10 (5)J
SEE QUESTION
If you have 51.5 g of a 50.0 cm3volume of one of the substances from the table above, which one is it? WITH GRAPH
Seawater
Why does a glass filled with a cold beverage seem to "sweat"?
The cold glass cools adjacent air to saturation, which is followed by condensation of water vapor.
If energy cannot be destroyed, why do some people worry about the energy supply?
The concern is with usable sources of energy
Why are fundamental frequencies and overtones also called resonance frequencies?
The fundamental and overtones are natural frequencies.
Why does a charged object have multiples of the fundamental charge?
The fundamental charge is the charge of one electron, and charged objects have a surplus or deficiency of electrons.
Which provides more cooling for a Styrofoam cooler, one with 10 lb of ice at 0°C or one with 10 lb of water at 0°C?
The ice provides more cooling because as ice undergoes the solid-to-liquid phase change it absorbs heat.
On a molecular level, how does the condensation of water vapor on a bathroom mirror warm the bathroom?
The latent heat is released during vapor-to-liquid phase changes.
What is resonance?
The matching of an external force with a natural frequency.
What eventually happens to a sound wave traveling through the air?
Their energy becomes dispersed as random molecular motion.
Why do astronauts on the moon have to communicate by radio even when close to one another?
There is no air on the moon, so no sounds are heard.
What is the difference between a joule of work and a joule of energy?
They are the same unit, which means that work and energy are the same thing.
Why are petroleum, natural gas, and coal called fossil fuels?
They formed from organisms that lived millions of years ago.
From time to time, people claim to have invented a machine that will run forever without energy input and develop more energy than it uses (perpetual motion). What is wrong with this claim?
This violates the law of conservation of energy
A horizontal force of 10 lb is needed to push a bookcase 7.7 ft across the floor. (a) How much work was done on the bookcase? (b) How much did the gravitational potential energy change as a result?
W (77) = ft lb ΔPE (0)= ft·lb
A force of 220 N is needed to push a table across a level classroom floor for a distance of 3.8 m. How much work was done on the table?
W = (840)J
Do all frequencies of sound travel with the same velocity?
Yes, if the wavelengths are constant according to v = λf.
Does a person standing motionless in the aisle of a moving bus have kinetic energy?
Yes, relative to the earth's surface the person has velocity.
Why does a piece of metal feel cooler than a piece of wood at the same temperature?
You sense heat flowing from your body as cool, and metal is a better conductor than wood.
What is happening when you walk across a carpet and receive a shock when you touch a metal object?
Your body is a poor conductor and you accumulate electrons until they are conducted away by a metal object.
The mechanical equivalent of heat is significant since it shows that
a certain amount of work always yields a predictable amount of heat.
The standard unit of TIME in the metric system is based on the
a certain number of vibrations of a cesium atom.
Which of the following involves an unbalanced force?
a force acting between two objects results in the acceleration of one
In which of the following would gravity not act normally? A room with
all the air removed. twice as much air pressure. three times as much air. +++++NONE OF THE ABOVE++++
Which of the following represents a concept of density?
compactness
The vacuum in the doubled-walled vacuum bottle takes care of heat flow by
conduction.
Would the tight packing of more insulation, such as glass wool, in an enclosed space increase or decrease the insulation value?
decrease, because there are fewer air spaces
Which of the following describes the use of an equation?
describe relationships between variables
The standard unit of LENGTH in the metric system is based on the
distance that light travels in a certain time in a vacuum.
A statement that describes a relationship between equal quantities is a (an)
equation.
A heat pump is able to move heat from a cooler region to a warmer region by
evaporating a refrigerant where you want it cooler, and then condensing it elsewhere.
Bending your knees as you hit the ground after jumping from a roof
extends the stopping time, which reduces the force.
A scientific theory is based on
extensive experimental evidence.
Disregarding air friction, what force(s) act on a bullet shot from a rifle as it moves through the air?
gravity
In which of the following is the net force zero?
grocery basket moves in a straight line at a uniform speed
A measure of the internal energy that has been absorbed or transferred from one body to another is
heat.
Materials become less dense as their temperature is increased because
increased energy results in molecules moving farther apart.
The total kinetic and potential energy of the molecules of an object is known as
internal energy.
What happens to the kinetic energy of a falling book when the book hits the floor? It
is converted to heat and sound.
What variables determine your weight?
mass and gravity
Cooler air is denser than warm air and flows downhill because
molecules of cool air are able to move closer together.
A mechanical wave is a disturbance that
moves through a medium such as a solid or the air.
What force is needed to maintain the speed of an object if there is no resistance?
none
Which of the following does not require work to be done? An increase in
none of the above
A measurement is correctly reported with a
number and a unit.
The silvered wall of a vacuum bottle takes care of heat flow by
radiation.
Your concept about an object is usually
represented by a word or words. ambiguous and not clear-cut. a generalized mental image of that object.
A cubic box is completely filled with 2179 g of water. What is the length of one side of the box, in meters? (0.13)m Explain your reasoning. Since the density of water is (1.00) g/cm3, then the volume of (2179) g of water is cm3. A cubic box with a volume of (2179)cm3 is (13)cm on each side. Converting (13)cm to meters, the cube is ().13)m on each side.
see question
A measure of the average kinetic energy of the molecules making up a substance is
temperature.
What is the relationship between the work done while moving a book to a higher bookshelf and the change of potential energy?
the increase equals the work done
Suppose you are standing on the frictionless ice of a frozen pond. How can you move off the ice?
throw something
Other than familiarity, an advantage of the English system of measurement is
units are based on body parts, which you always have with you.
Does sound travel faster in cold air or warm air? It travels faster in
warm air because molecules are moving faster and therefore carry information faster.
Which of the following has more entropy?
water vapor
When would a small car have the same momentum as a large truck?
when the velocity of the car is much greater than the velocity of the truck
What net force is needed to maintain the constant velocity of a car moving in a straight line?
zero
Without friction, what force is needed to maintain a 1000 kg car in uniform motion for 30 minutes?
zero
The upper limit of hearing for a particular human being is 20000 Hz. What is the corresponding wavelength if the air temperature is 23.2°C? Round answer to 4 decimal places.
λ= (0.0173)m
