Final Flashcards
0
Q
Does pushing a shopping cart qualify as doing work? (Assume there is friction.
A
Yes, you are applying a force against friction.
1
Q
Does climbing stairs classify as doing work?
A
Yes, because you are going against the force of gravity.
2
Q
What is the metric unit for work?
A
Joule
A joule is also a unit for energy
3
Q
If you exert a force of 10N to lift a box 2m, how much work did you do?
A
20 J
(10N)(2m)=20J
4
Q
What is the SI unit for power.
A
Watt
5
Q
If you exert a force of 5N to travel 10m in 2s how much power was used?
A
25W
(5N)(10m)/2s=25
6
Q
What can a machine multiply? (Two answers can apply)
A
Force, Distance
7
Q
How does a machine make it so that you can apply less force?
A
The machine allows you to apply the force over a greater distance.
Changes the direction of the force.
No matter what the total energy required to do the work must remain the same.
8
Q
How do you figure out the ideal mechanical advantage of a pulley system?
A
Count the number of rope segments that supports the weight.
10
Q
What is a machine that is made up of one or more simple machines called?
A
Compound Machine
11
Q
What is the energy of motion called?
A
Kinetic Energy
12
Q
I drop a ball that weighs 2 kg from a 3 m height. What is the balls gravitational potential energy?
A
About 60 J
EP=(2kg)(3m)(9.8m/s^2)
13
Q
What type of energy increases when an object gets warmer?
A
Thermal Energy
13
Q
The energy that is stored in coal is what type of energy?
A
Chemical
14
Q
This type of energy is defined as the total potential and kinetic energy of all the microscopic particles in an object.
A
Thermal Energy
15
Q
What type of energy supplies your body with energy?
A
Chemical energy that is stored in the food that you eat.
16
Q
The Sun uses what sort of energy?
A
Nuclear Energy
Similar, but opposite to the source of power for nuclear power plants.
17
Q
What energy conversion happens in the Sun?
A
Nuclear into Light
Solar cell convert light energy into electricity.
18
Q
How is temperature measured in the metric system?
A
Celsius Degrees, Kelvin
Celsius is based on the melting and boiling of water.
Kelvin is based on absolute zero.
19
Q
Thermal energy transfers from one substance to another because of differences in…
A
Temperature
20
Q
The measure of the average kinetic energy in an object, is the objects?
A
Temperature
22
Q
What three things affect an objects thermal energy?
A
Its mass phase and temperature.
23
Q
What is the difference between conduction, convection and radiation.
A
Conduction, convection, and radiation are all forms of heat transfer. The differences are in how the heat transfers. Conduction is through direct contact, convection is through fluid movement, and radiation is through electromagnetic waves.
24
Q
Is metal a good conductor or a bad conductor? Explain why.
A
Metal is a good conductor because it transfers heat and electricity well.
25
What is the name of the fluid that is found in air conditioners?
Refrigerant
26
What heating system involves heating water, and pumping it throughout a house?
Radiant Heating
As opposed to forced-air that involves a furnace and a blower.
27
A steam engine is an example of what kind of engine?
External combustion
Chemical energy is released outside of the engine which heats water into steam converting heat into work.
28
What does the first law of thermodynamics state?
That energy cannot be created or destroyed it only changes form.
28
What does the second law of thermodynamics state?
Thermal energy can flow from colder objects to hotter objects only if work is done on the system.
29
What does the third law of thermodynamics state?
Absolute zero can never be reached.
Absolute zero is where the subatomic particles cannot slow down any more.
30
What is the SI unit for force?
Newton
31
What is the total force on a tug of war rope if one team is pulling with 5N of force and the other team is pulling in the opposite direction with 5N of force?
10N of force.
32
What is the net force on a tug of war rope if one team is pulling with 5N of force and the other team is pulling in the opposite direction with 5N of force?
0N of force.
The forces are balanced.
33
What are two of the major forces that determine the speed of a parachutist?
The downward force of gravity, and the upward force of wind resistance.
35
What two things make thrown objects follow a curved path. (Projectile Motion)
The initial forward velocity of the abject, and the force of gravity.
36
Why would a car slide of the road in the wintertime?
If the forward inertia of the car is greater than the friction between the tires and the road, the car will slide of the road.
37
What does Newton's second law of motion state?
Force equals mass time acceleration.
38
What is the difference between weight and mass?
Mass is the measure of the amount of substance in an object. Weight is the measure of the force of gravity on a mass.
Weight equals mass times the force of gravity.
39
What does Newton's third law of motion state?
For every action there is an equal and opposite reaction.
40
What is the momentum of a 2kg toy car that is travelling at 3m/s?
6kgm/s
| m=m*v=2kg*3m/s.
41
What can a wave transfer?
Energy
| Mechanical Waves only transfer energy, and not particles.
42
Explain how you would measure frequency?
Pick a particular time period and count how many waves pass by over a certain time.
43
How would you measure amplitude?
Determine the distance between the rest position to either a crest or a trough.
44
What happens when a wave "bounces" off of a solid object?
Reflection
45
What happens when a wave changes direction because it has went from one medium to another?
Refraction
46
What happens when a wave passes through multiple openings and interferes with itself?
Diffraction
47
What happens when two waves occupy the same space?
The waves could build on each other (constructive interference) if the peaks and troughs line up.The waves could have destructive interference if the peaks and troughs are opposite of each other. Or anything in-between.
48
Describe the Doppler effect.
Objects moving toward you will make sounds in a higher pitch. Objects moving away will have a lower pitch.
49
What is the definition of one hertz?
A hertz is a wave per second.i.e. 5 hertz is five waves in a second.
50
What is the name for a wave that travels at the top of a given medium?
Surface Wave.
51
What kind of lines does a + sign have?What about an = sign?
+ perpendicular= Parallel
52
What three properties of a wave are different between red light and blue light.
Wavelength, Frequency, Energy
| All electromagnetic waves have the same speed, and reflecting properties.
53
What two things do you need to know about a wave in order to calculate its frequency?
The waves speed, and its wavelength.
54
What two things does an electromagnetic wave behave like?
A wave and a particle.
55
How do photons travel from a light source?
In all directions.
| Although once released light travels in a straight line.
56
The waves with the lowest frequency in the electromagnetic spectrum are the...
Radio waves
| They are longest wavelength, lowest frequency, and lowest energy.
57
The full range of frequencies of electromagnetic waves is the ...
Electromagnetic spectrum
58
Order the light transmitting properties of materials from all light to no light.
Opaque, Translucent, Transparent
Transparent, Translucent, Opaque
59
What is the term for when light changes direction when it passes from one medium to another?
Refraction
| This is why object that are place in water appear to be "bent".
60
How do polarized sunglasses work?
It blocks the light that vibrates in certain planes.
61
What determines the color of an object?
What it is made of and the color of light that hits it.
62
The primary colors of light are...
Red, Blue, Green
63
What gas is inside a fluorescent light?
Mercury
64
The human eye focuses light by...
Changing shape.
65
A compound microscope uses...
2 convex lenses to magnify a small object.
66
Which part of the eye focuses the incoming light rays.
Lens
| Lenses are used to focus light. Diaphragms/Apertures/Retina limit incoming light.
67
What type of images can a concave mirror form?
Virtual and real images
68
The point at which reflected rays intersect is the...
Focal point
69
What is the major difference between a real image and a virtual image?
A real image can be viewed on a screen.
70
Where do the light rays appear to be coming from in a plane mirror?
Behind the mirror.
71
What is a mirror with a flat surface called?
Plane mirror
72
What three things affect a materials resistance?
Thickness, Length, Temperature, (Composition)Resistance is a materials ability to conduct electrons
73
What does increasing the diameter of a wire do to its resistance?
It would reduce the resistance.Gauge is the measure for wire thickness. The lower the gauge the thicker the wire. Low gauge wire has less resistance.
74
If the current of a device is 2 amps and its resistance is 10 ohms what is the voltage of the iron?
20v(2 amps)(10 ohms)=20v
75
What is the purpose of a circuit breaker?
To open a circuit when the wattage flowing through the circuit gets too high. This prevents damaging devices that are plugged in to the circuit.
76
What is the purpose of a ground fault circuit interrupter? (GFCI outlet)
It shuts off a circuit in case of a short circuit.GFCI outlets should be used anyplace where water may get into an outlet.
77
The type of current that is supplied through wall outlets in the U.S. is...?
Alternating current. The direction of the current cycles 60 times per second (hz) in the U.S. Ever wonder why the plugs are different in Europe?
78
How many paths can electricity follow in a series circuit?
One
79
What type of current is produced by a battery?
Direct Current
| This type of current flows in one direction.
80
What happens when two objects of opposite charge are brought near each other.
They attract.They will also exchange charges to become more neutral.
81
What charge does an object take on when it gains electrons?
Negative
82
What is the name of the force that a magnet uses to hold your A paper on the refrigerator?
Magnetic Force
| Can be between magnets, magnets and magnetic substances, and magnets and moving charges.
83
How does the magnetic force between objects change as the distance between the two objects is decreased?
The magnetic force increases.Many other forces act the same way as the same amount of forceis spread out over a larger area.
84
What is the name of the area surrounding Earth that is influenced by the Earth's magnetic field?
Magnetosphere
85
What is the name for a ferromagnetic material that has domains that are aligned for a long period of time?
Permanent Magnet
| As opposed to temporary magnets that constantly need to be remagnetized.
86
What creates a magnetic field?
Moving electric charges.
87
What is the name of a device that converts mechanical energy into electricity?
Generator
A generator does this by moving a conductor through an electric field. (Electromagnetic induction)
88
How are fossil fuels used to generate electricity? (3 major steps)
Heat from burning fuel creates steam that spins a turbine (which is connected to a generator that makes electricity). The generator spins 60 time per second, making our AC current.
89
What is a solenoid?
A coil of wire that is carrying a current and producing a magnetic field.
90
Where is the magnetic force greatest on a bar magnet?
Toward the poles.
91
What determines the strength of the output voltage of a transformer?
The number of turns in the primary and secondary coils.
92
Why are step-up and step-down transformers used with power lines?
The step-up transformer increases the voltage of the electricity for easier transmission. The step-down transformer reduces the voltage for safer household use.
93
What happens to the force of gravity as the distance between two objects is increased?
The force of gravity decreases.
Gravity and distance are inversely proportional.
94
What two forces keep a planet in orbit?
Gravity keeps the planet from flying away. Momentum keeps the planet from falling towards the star.
95
What must a force do in order to do work.
It must create movement in the direction of the force.
96
What does the power rating tell you about something?
The items rate of doing work.
| i.e. horsepower in cars, wattage for appliances.
97
Why is the actual mechanical advantage of a machine always smaller than the ideal mechanical advantage of a machine?
No machine is 100% efficient at doing work so some advantage is always lost due to inefficiency.
98
What does oil do for an engine? Besides reducing wear and tear.
It reduces friction which increases the engines efficiency.
99
A motor uses 100 J of energy to accomplish 20 J of work. What is the motors efficiency?
20 % efficient.
(20/100)*100%
100
A knife is an example of what type of simple machine?
Wedge
101
What is transferred when work is done?
Energy
102
A 2 kg toy car is moving at 3 m/s. What is the cars kinetic energy?
9 J
(1/2)(2)(3)^2
103
What type of energy is represented by the following?
| A blown up basketball, A ball held a meter above the ground, a thrown ball.
Blown up basketball=elastic potential
A ball a meter above the ground= gravitational potential
A thrown ball= mechanical kinetic
104
What cannot be done with energy. (Two things)
Energy cannot be created or destroyed.
| This is the law of conservation of energy.
105
What is the term for energy that is stored in living things?
Biomass energy.
106
Are the following energy sources renewable or non-renewable?
| Nuclear, Wind, Hydroelectric, Geothermal, Oil
Nuclear is non renewable.
Wind, Hydro electric, and Geothermal are renewable.
Oil is renewable, but is being used at a much faster rate than what it is renewed.
107
How much energy is required to heat a substance if the specific heat of the substance is 0.5 j/gC. It weighs 2 kg, and you want to warm it up from 3C to 6C.
2j
| 0.5)(2)(6-3
108
What device is used to measure specific heat?
Calorimeter
109
What is the work done by a heat engine equal to?
The thermal energy that is put in to the engine minus the waste energy.
110
What happens when a substance reaches the temperature of absolute zero?
The total kinetic energy of the object is zero.
| The third law of thermodynamics states that absolute zero cannot be reached.
111
What is required to produce a wave?
Energy
112
Why so surfers get carried forward by waves even though waves normally do not carry particles?
The crest topples over because the wave is taller than the water is deep.
113
Arrange the following parts of the electromagnetic spectrum in order from lowest energy to highest energy waves.
Gamma, Infrared, Micro, Radio, Ultraviolet, Visible Light, X
Radio, Micro, Infrared, Visible Light, Ultraviolet, Gamma, X
Low energy waves have long wavelengths, and small frequencies.
114
How does the angle of reflection compare to the angle of incidence?
The angle of reflection is equal to the angle of incidence.
115
What sort of image can a concave lens form?
A virtual image.
| Mainly because the focal point is in front of the lens.
116
What property of a fiber optic cable allows it to transfer light over long distances?
Internal Reflection.
117
Arrange the following parts of the eye in order from the one that light first passes to the one that light hits last.
Cornea,Lens, Pupil, Retina
Cornea, Pupil, Lens, Retina
The cornea protects the eye, the pupil is a hole that allows light to pass into the eye, the lens focuses the light on the retina which sends messages to the brain.
118
What type of lens is used to correct for nearsightedness?
A concave lens that causes light to spread (diverge).
| Farsightedness is corrected by a convex lens that focuses light. (converge)
119
Why are power cords made of a metal that is surrounded by a rubber coating?
The metal acts as a conductor allowing the cord to transmit energy. The rubber coating insulates the wire stopping the electrons from passing to the outside.
120
Why are most of the circuits in your home set up in parallel?
Parallel circuits allow for certain circuits to be turned off without effecting other circuits in the house.
121
What is an integrated circuit?
A piece of silicon with solid state components.
