Transcript C - Fort Bend ISD

SPRING
SEMESTER
REVIEW
QUESTIONS
# 71 - 141
71. What are the classes of levers?
Where are the Effort forces,
Resistance forces and fulcrum for
each one? Give an example of
each.
72. What is a wedge? How can you increase
the mechanical advantage of a wedge?
an incline plane with 1 or 2 sloping sides;
make the wedge longer and thinner
73. What is the efficiency of a machine?
(Give the formula as well)
measure of the work put into a machine is
changed to useful work output (this can
never be 100% due to friction)
Eff= wo/wi X 100
74. A simple machine has an efficiency
of 88%. What will be the machine’s
work output if the input is 5000 J?
Eff= 88%
wo = ?
wi = 5000J
wo = (5000 J) (.88) = 4400 J
75. How can you increase the efficiency
of a machine? (What can you get rid
of?)
use a lubricant to reduce the friction
76. What simple machines can you
basically put in the same group
together? Why can you do this?
incline planes, levers, wedges and
screws; they are all incline planes
77. What is a thermal insulator?
they do not transfer heat by contact
very easily
78. What is radiant energy?
the transfer of energy by
electromagnetic waves
79. What are the three types of heat
transfer? Give an example of each.
conduction – iron on a shirt
convection – heating of a liquid
radiation – sun warms the earth
80. List some good insulators.
wood, plastic, glass, air
81. List some good conductors.
silver, copper, aluminum (all metals)
82. What is resistance? What is the unit
for resistance?
tendency of a material to oppose the
flow of electrons; changes electrical
energy into thermal Energy;
unit- Ohms (Ω)
83. Convert -273˚C to Kelvin.
˚C + 273 = ˚ K
-273˚C + 273 = 0 ˚K
84 Convert -225˚ F to Celsius.
(˚F – 32)( 0.56) = ˚C
(-225 ˚F -32) (0.56) = -143.92 ˚C
85. Convert 33 °C to Fahrenheit.
(°C X 1.8) + 32 = °F
(33 °C X 1.8) + 32 = 91.4 °F
86. As the temperature increases,
What happens to the molecular
movement?
the molecular movement increases
87. What is a phase change?
where heat is added or taken away,
but the temperature does not
change; a substance changes the
state of matter
88. Draw a phase change diagram. Label
the following: melting point, boiling point,
freezing point, heat of vaporization, heat of
fusion, solid, liquid, gas.
89. What is specific heat?
the ability of a substance to
absorb heat energy; the amount
of heat needed to raise the
temperature of 1 kg. of some
substance by 1 °C
90. A piece of lead loses 90 J of heat
and experiences a decrease in
temperature of 11 °C. What is the
mass of the piece of lead? (The
specific heat of lead is 0.13 J/°C)
Q= 90 J Δ t= 11°C
c= 0.13 J/g°C
m = Q / c Δt
90 J
= 62.94 g
(0.13 J/g°C ) (11°C)
91. What is temperature? What is
heat?
relates the average KE of the
molecules in a substance; the
sum of the KE and PE of all
molecules in an object (depends
on temperature and mass)
92. What is series circuit?
a path where the current has only
one loop to flow through; any
breaks in it opens the circuit and
nothing works
93. What is a parallel circuit?
a path with two or more branches
for electrons to flow; a break in
one part does not affect the rest
94. What are three differences
between series & parallel circuits?
1. number of loops
2. If one light goes out in series,
nothing works—the rest will
continue to burn in a parallel
circuit
3. the was that it is connected
95. What is the definition of static
electricity? What are the three
methods of charging?
an accumulation of excess charges
on an object;
1. friction-rubbing
2. conduction – touching
3. induction- near but not touching
96. What is direct current?
flow of electrons through a
conductor in one direction
97. What is alternating current?
the back and forth movement of
electrons in a wire
98. A 40 V battery is connected to a
circuit in which a current of 30 A
flows. What is the resistance of
the circuit?
V= 40V
I = 30A
R= ?
R= V/I = (40V) / (30A) =1.33Ω
99. How much voltage is needed to
power a 600 W appliance that
uses a current of 11.2 A?
V= ? P=600Watts I= 11.2Amps
V= P/I = (600W) / (11.2A)
= 53.57 Volts
100. The power rating on an iron is
3500 W. At $0.60 /kWhr, how much
does it cost to leave the iron on for 3
hours?
P= 3500W cost/kWh = $0.60 t=3hr
E= Pt = (3.500 kW)(3 hr) = 10.5 kWh
Total Cost = E x cost/kWh
= (10.5 kWh) ( $0.60/ kWh)
= $6.30
101. A television that requires an
average of 6 A of current is operated
on a 120 V service for 2 hours. How
much energy is used?
I= 6Amps V=120Volts t=2hr E=?
P= IV= (6 A)(120 V) = 720 W= 0.72 kW
E = Pt = (0.72 kW) (2 hr) = 1.44 kWh
102. The location of the strongest
magnetic forces is at the _____.
Poles
103. Draw the magnetic field lines for
the following diagrams:
104. What are the three methods of making a magnet?
Stroke in one direction, induction, electricity
105.
What are three ways to destroy a magnet?
Stroke back and forth, heat, hammer
106.
When a neutral object gains electrons it forms a __________ charge?
negative
107.
A force of attraction exists between what two parts of an atom?
electrons and protons
108.
The region around a magnet where the magnetic forces act is the?
Magnetic field
Repeating
disturbance or movement that transfers
energy through matter or space
109. What is a wave?
110. On the following diagram, identify
wavelength, crest, trough, resting point
and amplitude.
C
D
E
A
B
A. Resting point
D. Wavelength
B. trough C. Crest
E. amplitude
111. What does a wave carry?
Energy
112. What is a mechanical wave?
A Mechanical wave, made up of a
series of compressions and
rarefactions
And needs a medium through which
to travel
113. What is a transverse wave ?
Draw an example.
A wave that does not need a medium
made up of troughs and crests
114. What is the Law of Reflection?
The angle of incidence is equal to
the angle of reflection
115. What is Reflection?
When a wave hits a barrier
and bounces off
116. What is Refraction?
A wave changes speed as it
goes from one medium to
another and bends
117. What is Resonance?
When a material vibrates at its
natural frequency
118. What is the Doppler Effect?
Give an everyday example of
where you see/hear this.
The change in pitch or wave
frequency when a sound and its
receiver move relative to one
another. Ex-siren passing by
119. What is Echolocation?
What animal uses this to hunt?
Process of locating objects by
emitting sounds and
interpreting the sound that
reflects. Bats and dolphins
120. What is Sonar?
A system that uses sound waves
to detect objects under water.
121. What waves are used in
medical imaging?
Ultrasound, radio, x-rays, gamma
rays
122. What is the wavelength of a 42
Hz wave traveling at 990 m/s?
Wavelength = speed / frequency
= 990 / 42 = 23.57 m
123. Why can a bell ringing in a
vacuum chamber not be heard?
Sound waves need a medium and
there are no particles to vibrate on
in a vacuum
124. For the speed of a wave to remain
constant, an increase in wavelength
requires a corresponding what?
There must be a decrease in
wavelength
125. The interaction between two
waves arriving at the same the
point at the same time is called
Interference
126. Sound is what kind of
wave?
Compressional
127. The speed of sound in air is
slower or faster than the speed of
light in air?
Slower
128. What is loudness?
The human perception of sound
intensity
129. Intensity of a sound is directly
related to what?
Amplitude
130. What is pitch?
The highness or lowness of a
sound, depends on frequency
131. Sounds that cause pain in
humans have intensities as great
as? 120dB (decibels)
132. Electromagnetic waves are
what kinds of waves?
Transverse waves
133. What does your body need
in order to make Vitamin D?
Sunlight-UV radiation
134. What are the primary light
colors?
Red, blue, green
135. How does a rainbow form?
Raindrops act as tiny prisms
and as sunlight goes through the
raindrop it is refracted, the light
bends the light separating it into
the color spectrum.
136. List the parts of the electromagnetic
spectrum in order of increasing energy.
Radio, infrared, visible light,
ultraviolet, x-rays, gamma rays
137. What part of the electromagnetic
spectrum is used for communication?
Radio
138. What is transparent? Give an
example of something that is
transparent.
Transparent is when all the light
passes through a material easily.
(See through) Examples are
plastic wrap, a window, a
transparency
139. What is translucent? Give an
example
Materially that allows some light to
pass through. (Partially see through
it) Examples: waxed paper, show
curtain
140. Why do you see a rose as red?
When white light hits a rose all the
colors are absorbed except red, red
is reflected & that is what we see
141. What is the difference
between a mirror and a lens?
Mirror: light hits it and bounces
off
Lens: light passes through it