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135 Cards in this Set

  • Front
  • Back
In science, an educated guess is
hypothesis
In science, facts
may change
Compared with the mass of a certain object on Earth, the mass of the same object on the moon is
the same
The gain in speed each second for a freely falling object (without air resistance) object is about
10 m/s
Which has zero acceleration? An object
at rest
moving at a constant velocity
in mechanical equilibrium
What is the acceleration of a car that maintains a constant velocity of 100 km/h for 10s
0
If a freely falling ( without air resistance) object were somehow equipped with an odometer to measure the distance it travels, then the amount of distance it travels each succeeding second would be
greater than the second before
One object has twice as much mass as another object, and also has twice as much
inertia
The scientist to first introduce the concept of inertia was
Galileo
A kilogram is a measure of an object's
mass
An object travels 8 m in one second of travel, 8 m again during the next second of travel, and 8 m again during the following second. It's acceleration in meters per second is
0
A 2-kg mass at the Earth's surface weighs about
20 N
It takes 8 s for a stone to fall to the bottom of a mine shaft. Disregarding air resistance, how deep is the shaft?
about 320 m
A 500-kg bear grasping a vertical tree slides down at constant velocity. The friction force between the tree and the bear is
5000 N
A pot falls from a ledge and hits the ground 80 m below. Neglecting air resistance, the speed with which it hits the ground is about
40 m/s
A 20-N falling object encounters 6-N of air resistance. The magnitude of the net force on the object is
14 N
A sheet of paper can be withdrawn from under a container of milk without toppling it if the paper is jerked quickly. This best demonstrates that
the milk carton has inertia
A skydiver, who weighs 400 N, reaches terminal velocity of 90 km/h. The air resistance on the diver is then
400 N
When a falling object has reached its terminal velocity, its aceleleration is
0
A heavy object and a light object are dropped at the same time from rest in a vacuum. The heavier object reaches the ground
at the same time as the lighter object
A player hits a ball with a bat. The action force is the impact of the bat against the ball. The reaction to this force is the
force of the ball against the bat
A car has a mass of 2000 kg and accelerates at 3m/s/s. What is the magnitude of the force exerted on the car?
6000 N
A skydiver steps from a helicopter and falls for 5 s before reaching her terminal velocity. During this 5 s interval, her acceleration
decreases
Careful: On the surface of Jupiter, where the acceleration dur to gravity is about 3 times that of Earth, a 100 kg rock would have a mass of about
100 kg
A bag of groceries has a mass of 15 kg and a weight of about
150 N
According to Newton's law of inertia, the result of walking much of the day is similar to tightening the head of a hammer when its handle hits a solid surface so that we should be a little bit shorter in the
evening
A 5 kg block is pushed across a horizontal force os 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is
2
On the surface os Jupiter, where the acceleration due to gravity is about 3 times of Earth, a 100 kg rock would have a weight of about
3000 N
If you are carrying a heavy bag of groceries and bang your hand against the wall, the concept that most explains why your hand is hurt is
inertia
An object is raised above the ground gaining a certain amount of potential energy. If the same object is raised twice as high, it gains
twice as much potential energy
A freight train rolls along a track with considerable momentum. If it rolls at the twice the velocity but has no change in mass, the momentum is
doubled
Which of the following has the most momentum
a marble rolling across the floor
If you push an object four times as far while applying the same force, you do
four times as much work
When you are in the way of a fast moving object and can't get out of the way, you will suffer a smaller force of impact if you can decrease its momentum over a
longer time
An object that has kinetic energy must be
moving
A car moves twice as fast as another identical car with identical mass. Compared to the slower car, the faster car has
4 times the KE
A ball is moving at 4 m/s and has a momentum of 24 kg m/s. What is the balls mass
6 kg
A moving object has
speed
velocity
momentum
energy
A piece of putty moving with 1 unit of momentum strikes and sticks to a heavy bowling ball that is initally at rest. After the putty sticks to the ball, both move with a combined momentum of
1 unit
A 4 kg mass is held 5 m above the ground. What is the approximate potential energy of the mass with respect to the ground?
200 J
A car moving at 50 km/h skids 25 m with locked brakes. How far will the car skid with locked brakes if it is traveling at 100 km/h?
100 m
A popular swinging balls apparatus consists of an aligned row of identical steel balls that are suspended by strings so they barely touch each other. When two balls are lifted from one end and released, they strike the row and the two balls pop out from the other end. IF instead one ball popped out with twice the speed of the two, this would be a violation of conservation of
energy
A positive ion has more
protons than electrons
A main difference between gravitational and electric forces is that electrical forces
repel or attract
The electrical force between charges is strongest when the charges are
close together
Charge carriers in a metal are electrons rather than protons because electrons are
loosely bound
A charged balloon neatly illustrates that something can have a great amount of
voltage and a small potential energy
An ampere is a unit of electrical
current
the current in a 100 W bulb connected to a 120 V source is
.83 A
The current through a 10 ohm resistor connected to a 120 V power supply is
12 A
The electric power of a lamp that carries 2 A at 120 V is
240 W
As more lamps are put into a series circuit, the overall current in the power source
decreases
As more lamps are put into a parellel circuit, the overall current in the power source
increases
Which is more dangerous, touching a faulty, underground 110 V light fixture or a Van de Graaff generator charged to 100,000 V? Touching the
light fixture
Rub electrons from your hair with a comb and the comb becomes
negatively charged
The source of all magnetism is
moving electric charges
Like kinds of magnetic poles repel while unlike kinds of magnetic poles
attract
Magnetism is due to the motion of electrons as they
move around the nucleus and spin on their axes
In terms of the way they are constructed, an electric motor and electric generator are
very similar devices
When there is a change in the magnetic field in a closed loop of wire,
a voltage is induced in the wire
current is made to flow in the loop of wire
electromagnetic induction occurs
Voltage can be induced in a wire by
moving the wire near a magnet
moving a magnet near the wire
changing the current in a nearby wire
A device that converts electrical energy to mechanical energy is a
motor
Transformers use ac so there will be the required
change in magnetic field for operation
The voltage across the primary terminals of a transformer is 110 V. The primary has 50 loops and the secondary has 100 loops. The voltage the transformer puts out it
220 V
Four amps of current exist in the primary coil of a transformer. The voltage across the primary coil is 110 V. What is the power output of the secondary coil?
440 W
A certain transformer doubles input voltage. If the primary coil has 20 A of current, then the current in the secondary coil is
10 A
Where does most rainfall on the earth finally end up before becoming rain again?
the oceans
What is an advantage of using chlorine gas to disinfect drinking water supplies?
it provides residual protection against harmful bacteria
Why is it important to conserve fresh water?
there is little fresh water available to us on the planet

as the human population grows, so does our need for fresh water

it is expensive to purify water for drinking
How are the disinfecting properties os ultraviolet light and ozone similar to each other?
neither provides residual protection against harmful bacteria
In wastewater treatment, we try to allow aerobic bacteria to predominate. Aerobic bacteria are those that
do need oxygen in order to live
of the total amount of water contained in the earth, how much of it is readily available as a source of fresh water supply?
less than 1%
the natural circulation of water in nature - from the oceans to the air then to the ground then to the oceans and then to the atmosphere is called the
hydrologic cycle
Solids removed from wastewater treatment can be used as
incinerator fuel
landfill
fertilizer or soil conditioner
most of the earths fresh water is located in
polar ice caps and glaciers
raw sewage is comprised mainly of water. on the average, how much water is in raw untreated sewage?
99.9%
evaporation from the oceans produces clouds that precipitate fresh water rather than saltwater because
evaporation produces nearly pure water vapor
a treatment chemical that is added to many municipal water supplies for the purpose of aiding and enhancing dental hygeine is
fluoride
in wastewater treatment, we are compressing the natural treatment processes from nature in both
time and space
some thunderstorms supercells will spawn tornadoes while others, even under similar conditions, will not. The reason for this phenomenon cannot yet be fully explained by meterological scientists and researchers.
true
tornadoes are most common in a region known as tornado alley which is located
over the central US
when a funnel cloud touches the ground it becomes a
tornado
a power line with a resistance of 2 ohms has a current of 80 A in it. The power dissipated in the line is
12,800 W
A 60 W light bulb and a 100 W light bulb are each connected to a 120 V outlet. Which light bulb has more current in it>
the 100 W bulb
According to Newtin, the greater the masses of interacting objects, the...
greater the gravitational force between them
If the mass of the Earth somehow increased with no change in radius, your weight would
increase also
Inside a freely falling elevator, there would be no
apparent weight for you
If the radius of the Earth somehow decreased with no change in mass, your weight would
increase
Two objects move toward each other because of gravity. As the objects get closer and closer, the force between them
increases
The reason the moon does not crash into the earth in that
the moon has sufficient tangential velocity
How far must one travel to get away from the earth's gravitational field>
Forget it; you can't travel far enough
A stone is thrown horizontally from the top of a cliff. One second after it has left your hand its vertical distance below the point where it left your hand is
5 m
An Earth satellite is simply a projectile freely falling around the earth
true
a bullet fired horizontally hits the ground in .5 seconds. If it had been fired with twice the speed in the same direction, it would have hit the ground in
.5 seconds
Earth satellites are typically more than 100km high so as to be above the earth's
atmosphere
A satellite near the earth makes a full circle in about an hour and a half. How long would a satellite located as far away as the moon take to orbit the earth?
about 28 days
communications and weather satellites always appear at the same place in the sky. This is because the satellites are
rotating the earth once every 24 hours
a dam is thicker at the bottom than the top because
the pressure of the water is greater with increasing depth
One liter of water has a mass of
1 kg
a completely submerged object always displaces its own
volume of fluid
when an object is immersed in a liquid, it is buoyed up by
a force equal to the weight of the fluid it displaced
a lobster crawls onto a bathroom scale submerged at the bottom of the ocean. compared to its weight above the surface, the lobster will have an apparent weight on the underwater bathroom scale that is
less
buoyant force is greatest on a submerged
same on each whether it be a cm^3 of aluminum or lead
atmospheric pressure is caused by the
weight of the atmosphere
the air in this room has
mass
weight
energy
airplane flight is best illustrated by
Bernoulli's principle
an umbrella tends to move upwards on a windy day principally because
air pressure is reduced over the curved top surface whih in effect exerts a force upward on the underside of the umbrella
in a vacuum, an object has no
buoyant force
suspend a pair of ping pong balls from two strings so there is a small space bewteen the two and blow air through the space. Which way will they swing?
towards each other
A substance that heats up relatively quickly has a
low heat capacity
heat energy is measured in
joules and calories
ice tends to form at the
surface of the water
the reason why the white hot sparks that strike your skin from a 4th of July type sparkler don't harm you is because
the energy per molecule is high but the total energy transfer is minimal
the moderate temperatures of islands throughout the world has much to do with waters
relatively high heat capacity
before ice can form on the surface of bodies of water, all of the water must be
4C
blow on your hand with an open mouth and the air is warm. pucker your lips and your breath is
cooler
consider a sample of water at 0 degrees C. If the temperature is slightly increased, the volume of water
contracts
a substance can absorb heat energy in by the processes of
conduction
convection
radiation
if a volume of air is warmed it expands. If air expands it
cools
evaporation is a cooling process. condensation is a
warming process
we are warmed by condensation because water molecules in the air that strike our bodies
give off some of their kinetic energy
when heat is added to boiling water, the water temperature
stays the same
consider a steaming aluminum soda-pop can that contains a small amount of boiling water. When it is quickly inverted, the can is dramatically crushed by atmospheric pressure. this occurs because the pressure in the can is rapidly reduced by
condensation in the can
inreasing the temp of 50 grams of water by 10 degrees requires
500 calories
What is the planetary lineup for a solar eclipse?
the moon is directly between the sun and the earth
What is the planetary lineup for a lunar eclipse?
the earth is directly between the moon and the sun and the earths shadow is cast on the moon
What roles do nuclear fusion and gravity in stars play?
nuclear fusion and gravity work together to keep the star together. Nuclear fusion pushes the limits of the star out and gravity hold it all togther. When the nuclear fusion begins to dwindle, slowly gravity takes more of a part and the star everntually collapses
When the new moon arrives and you are on the noon side of the globe, can you see the new moon?
no
How often does the earth make a full rotation?
every 24 hours
How often does the moon rotate on its axis?
about every 28 days
In a lunar eclipse, what would you see? On the moon?
from earth, you see the colors oranges and reds because the earths atmosphere refracts most of the colors, from the moon you would see all the sunsets and rises of the earth
What is Polaris and where in the sky is it found?
Polaris is the North Star and is located directly above the north pole
When a star supernovas and becomes a black hole, does the mass of the star change significantly?
no
What different star colors correspond with different heat levels?
cooler stars - red (red giants)
medium temperature stars - white
hot - bluish white
What is a solar wind?
auroras -- have to do with sun radiation