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Transcript
Physics 20 Year End Review
Kinematics
Each number represents a word. Write the word that best completes the statement.
A(n) (1) ____________ quantity is completely described by its magnitude. A(n) (2) ____________ quantitiy has both
magnitude and direction. Velocity and displacement are example of (3) ____________ quantities. The sum of two vector
quantities is determined by their (4) ____________ and magnitudes. The length of the arrow-tipped line segment drawn to
representa vector is proportional to the (5) ____________ of the vector. Vectors can be added by placing the (6)
____________ of one vector at the head of the other. When vectors are added, the (7) ____________ is drawn from the tail of
the first vector to the head of the second vector. A person walks around a city. The vector drawn from the starting position to
the final position represents the (8) ____________. Speed represents the magnitude of (9)____________. The rate of change
of velocity is called (10)____________. A car travels 750 km in 10 hours. The (11) ____________ speed of the car is 75
km/h. The (12) ____________ velocity of an object in motion is its velocity at any given instant of time. (13) ____________
can be computed by dividing an objects change in velocity by the time necessary to make that change. The SI unit for
acceleration is (14)____________. An object that is slowing down is said to have a(n) (15) ____________ acceleration. The
final velocity of a uniformly accelerating body which started from rest is equal to its acceleration multiplied by
(16)____________ . The acceleration due to gravity has a value in SI units of (17)____________ . The average velocity of an
object undergoing (18) ____________ acceleration can be calculated by adding the initial and final velocities and dividing by
two.
Problems
1. How many seconds would it take a boat to accelerate from 13 m/s to 26 m/s over a distance of 1.25 km? (64 s)
2. A racing car traveling initially at 8.0 m/s accelerates uniformly at 10.0 m/s2 for 5.0 seconds. How far does it travel in
this time interval? (1.7 x 102 m)
3. A ball is hit straight up in the air with an initial velocity of 38 m/s.
a) How long does it stay in the air? (7.7 s) b) How high does it go? (74 m)
4. A racing car travels 480 km in 2.00 h. Calculate the cars average speed in km/h and m/s. (240 km/h, 66.7 m/s)
5. A cart, initially at rest, accelerates at a rate of +3.0 m/s2 for 8.0 s.
a) How fast is the cart traveling after 8.0 s? (+24 m/s) b) How far has the cart traveled? (+96 m)
6. A gun is fired and the bullet is accelerated in the gun barrel, which is 1.00 m long. The bullet leaves the barrel with a
velocity of 600.0 m/s. Calculate the acceleration of the bullet while it is in the barrel. (1.80 x 105 m/s2)
7. A ball is dropped from a roof and takes 3.0 s to reach the ground. Calculate the elevation of the roof above the ground
in meters. (Neglect air resistance). (44 m)
8. A projectile is shot straight up with a velocity of 58.8 m/s. (Neglect air friction).
a) Calculate the velocity of the projectile 1.5 s after firing. (44 m/s)
b) How high above the gun is the projectile 1.5 s after firing? (77 m)
c) How high is the projectile 9.0 s after firing? (133 m)
d) Calculate the velocity of the projectile 9.0 s after firing. (-29 m/s)
9. A boy standing on a 19.6 m tall bridge sees a motorboat approaching the bridge at a constant speed. When the boat is
27 meters from the bridge, the boy drops a stone to the water below. If the stone strikes the water 3.0 meters in front
of the boat, at what speed was the boat traveling? (12 m/s)
Each number represents a word. Write the word that best completes the statement.
For an object moving at a(n) (1) ____________ speed, the distance traveled is directly proportional to the elapsed time. The
steepness of a graph line is called the (2) ____________ of the graph. The slope of a position-time graph yields the (3)
____________ of the moving object. The slope of a straight line is (4)____________. As the velocity of an object increases,
the slope of the line on the position-time graph (5)____________. When the slope of the line on a distance-time graph is (6)
____________ the object involved is at rest. On a(n) (7)____________ -time graph, the area between the line of the graph and
the horizontal axis respresents the displacement of the object. With constant acceleration, the curve of a(n) (8)-____________
time graph is a half parabola. The slope of the line on a velocity-time graph shows the (9) ____________ of a moving object.
With constant acceleration, the distance an object travels varies directly with the (10)____________. The area between the
graph line and the horizontal axis on a(n) (11)____________ -time graph represents the change of velocity of the object in a
given time interval. A negative acceleration might mean that the object is speeding up while going in the (12) ____________
direction. Straight lines on a position-time graph indicate that no (13) ____________ occurs.
Vectors and projectiles
Each number represents a word. Write the word that best completes the statement.
Force, like a velocity and displacement is a (1) ____________ quantity. A (2) ____________ quantity can be represented by
an arrow-tipped line segment. Vectors can be (3) ____________ by placing the tail of one vector to the head of the other
vector. When adding two vectors, neither the length nor the (4) ____________ of the vector is changed. The sum of two
vectors, or the (5)____________ , is found by drawing a third vector from the tail of the first vector to the head of the second.
If two vectors act in the same or in (6) ____________ directions, their vector sum can be found algebraically. If two vectors
act perpendicularly, the magnitude of the resultant vector can be used using the (7) ____________ theorem. If three different
7.0 N forces act simultaneously on the same ojbect, the resultant vector can be no greater than (9) ____________ Newtons. An
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object is in (10) ____________ when the vector sum of the forces acting on it is zero. An object that is thrown into the air is
called a (11)____________ . The vertical and horizontal motions of a preojectile shot into the air are (12) ____________ of
one another. Because of inertia, the (13) ____________ velocity of the projectile is constant. The time required for a
projectile to strike the ground depends on the original height, the initial (14) ____________ velocity and the acceleration due
to gravity. Two golf balls are released at the same time from the same height. One ball is dropped vertically while the other is
projected horizontally. The (15) ____________ of the two balls is always the same.
Problems
1. A motorboat heads due west at 10.0 m/s. The river has a current of 6.00 m/s south.
a. What is the resultant velocity of the boat? (11.7 m/s, 31.0˚ S of W)
b. If the river is 200 m wide, how long does it take the boat to cross the river? (20.0 s)
c. How far downstream is the boat when it reaches the other side? (120 m)
2. A child is pulling on a rake with a force of 45 N at an angle of 50˚ with the horizontal.
a. What is the horizontal component of the force? (29 N)
b. What is the vertical component of the force? (34 N)
3. A bullet traveling 800 m/s horizontally hits a target 180 m away. How far does the bullet fall before it hits the
target? (0.248 m)
4. A ball is thrown vertically upward and rises to a maximum height of 100 m.
a. What was the initial speed? (44.3 m/s)
b. What is the speed at 60.0 m above the ground? (28.0 m/s)
5. A cannon is mounted on a castle wall 80.0 m above the ocean. An enemy ship is 300 m from the shore. The
cannon can fire 10.0 kg shells at a velocity of 42.0 m/s. If the cannon is aimed at a 40.0˚ angle with the horizontal
calculate the following:
a. How high will the shell reach? (117 m)
b. What is the shell’s vertical velocity at 20.0 m above the sea? (43.7 m/s)
c. Will the shell reach the enemy ship? (no, 246 m)
6. A 2.0 kg projectile is fired from a cliff 50.0 m high with a speed of 80.0 m/s. The projectile is fired at an angle
30.0˚ to the horizontal. Calculate : a) vertical kinetic energy (1.6 x 103 J) b) vertical kinetic energy at a point
20.0 m above the ground. (2.2 x 103 J) c) speed at 20.0 m above the ground. (47 m/s)
7. A projectile is fired at 300 m/s at an angle of 60.0˚ to the horizontal. Calculate:
a) maximum height reached. (3.44 x 103 m) b) time of flight (53.0 s) c) range (7.95 x 103 m)
d) height after 20.0 s (3.23 x 103 m)
8. A camper dives from the edge of a swimming pool at water level with a speed of 8.0 m/s at an angle of 30.0˚
above the hoizontal.
a. How long is the diver in the air? (0.82 s)
b. How high does the diver go? (0.82 m)
c. How far out in the pool does the diver land? (5.7 m
Forces
Each number represents a word. Write the word that best completes the statement.
(1) ____________ and Galileo contributed most to our understanding of motion. A change in the state of motion of an object
is caused by a(n) (2)____________ . (3) ____________ is the study of motion without regard to forces. (4) ____________ is
the study of the relationships that exist between forces and the motion of objects. (5) ____________ is the property of an
object which causes it to resist all changes in its state of motion. Unless acted upon by a(n) (6) ____________ an object is at
rest or in a state of uniform motion will remain at rest or in uniform motion. An object is (7) ____________ when an
unbalanced force acts on it. A net force of one (8) ____________ gives a mass of 1.0 kg an acceleration of 1.0 m/s2.
Acceleration of an object varies directly with the applied force and inversely with the (9) ____________ of the object. (10)
____________ is the measurement of the gravitational force acting on an object. (11) ____________ depends upon the
amount of matter in an object and is independent of the location of the object. (12) ____________ is a force that opposes the
motion of an object. The force of friction depends upon the type of surfaces in contact and the (13) ____________ force.
Complete the following statement <Every force is accompanied by a(n) (14)____________ .>
Problems
1. What is the mass of an object that is accelerated at 25 m/s2 by a force of 125 N? (5.0 kg)
2. A brick has a mass of 1.2 kg. A force of 5.4 N is needed to move the brick along the floor with a constant
velocity. What is the coefficient of friction? (0.46)
3. The coefficient of friction for wood on wood is 0.55. What is the force of friction of a wood block on mass 3.5
kg being pulled on a wood floor? (19 N)
4. A stone weighs 5.4 N. What force must be applied to make it accelerate upward at 3.0 m/s2? (7.1 N)
5. What is the greatest upward acceleration a 70.0 kg boy climbing a rope can attain without breaking the rope if the
rope can support 1.00 x 103 N? (4.4 m/s2)
6. A man wants to escape from a burning building by sliding down a rope which can only support 400 N. If the man
weighs 800 N, what is the smallest acceleration he can have and not break the rope? (-5.0 m/s2)
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7.
8.
9.
10.
11.
12.
13.
14.
15.
If a horizontal force of 30.0 N is required to slide a 12.0 kg wooden crate across the floor at a constant velocity,
what is the coefficient of friction between the floor and crate. (0.255)
A 70.0 kg astronaut is standing on a scale in a spaceship. While the ship is moving in a straight line with a
constant velocity of 100.0 m/s near a large planet, the scale reads 300.0 N. The ship then accelerates away from
the planet at 7.0 m/s2. What does the scale read? (7.9 x 102 N)
A 10.0 kg mass on a frictionless table is accelerated by 5.0 kg mass hanging from the table. Calculate the
acceleration of the 10.0 kg mass. (3.3 m/s2)
An elevator is traveling upwards at a constant speed. What is the apparent weight of a 50.0 kg child? (491 N)
A 68.9 kg woman is standing on a Newton scale in an elevator when it begins to move upward. If the elevator
reaches a speed of 8.00 m/s after 20.0 s, what is the reading on the scale? (703 N)
An Atwood’s machine has a 5.30 kg mass and a 3.00 kg mass attached to it.
a. What is the acceleration of the system? (2.72 m/s2)
b. If the pulley has a frictional force of 2.90 N in the above system, what is the acceleration ? (2.37 m/s2)
A Fletcher’s trolley has a 50.0 kg mass on a frictionless table. A 60.0 kg mass hangs over the edge of the table.
a. What is the acceleration of the mass on the table? (5.35 m/s2)
b. If the coefficient of friction between the table and the 50.0 kg mass is 0.459, what is the acceleration of the
system? (3.30 m/s2)
An Atwood’s machine has a 400 kg mass and a 390 kg mass attached. What must the frictional forces in the
pulley be if the system does not move? (98.1 N)
A Fletcher’s trolley has a 10.0 kg mass on a table where the coefficient of friction is 0.777. What mass must be
overhanging such that the acceleration of the system is 4.50 m/s2? (22.8 kg)
Gravitation
Each number represents a word. Write the word that best completes the statement.
(1) ____________ an excellent mathematician, formulated three laws of planetary motion. The paths of the planets around the
sun are (2)____________ . The average (3) ____________ of a planets orbit cubed divided by the planets period squared is
equal to a constant. (4) ____________ was the first person to believe strongly that the behavior of all material bodies is
governed by the same universal laws. Every body in the universe attracts every other body with a force that varies (5)
____________ with the product of the masses. Gravitational attraction varies (6) ____________ with the square of the
distances between masses. Newton was able to use information concerning the moon to test and verify his (7)____________ .
(8) ____________ is another name for the gravitational force of attraction between the earth and mass. The (9) ____________
due to gravity is the same for all objects near the surface of the earth.
Problems
1.
The value for K for planets moving around our sun is 3.35 x 1018 m3/s2. If Neptune’s orbit has an average radius
of 4.5 x 1012 m, calculate the period of Neptune. (1.6 x 102 Earth years).
2. The gravitational force between two electrons 1.00 m apart is 5.42 x 10-71 N. Calculate the mass of each electron.
(9.01 x 10-31 kg)
3. A 90.0 kg person is spinning around on the equator of planet X, which is rotating at 3.2 x 103 km/h. The
centripetal force holding the person in place is 6.0 N. What is the radius of planet X? (1.2 x 107 m)
4. The radius of the earth is about 6400 km. What would be the earth’s gravitational attraction on a 75.0 kg
astronaut in an orbit 6400 km above the earth’s surface. (180 N)
5. The radius of a planet is 3400 km. If an object weighs 550 N at the surface of the planet, what is its weight at
a) 12 km above the surface? (546 N) b) 210 km above the surface? (490 N)
6. Neptune has a mass of 1.02x1026 kg and a radius of 2.48x107 m. Calculate the gravitational field on the surface.
(11.1 N/kg)
7. Jupiter and Saturn are 6.49x1011 m apart. Calculate the net gravitational field midway between them. Data for
Jupiter- mass 1.90 x 1027 kg, radius 7.15 x 107 m Saturn- mass 5.69 x 1026 kg, radius 6.03 x 107 m
(7.47x10-7 N/kg toward Jupiter)
Circular Motion
A (1) ____________ force is needed to make an object move in a circular path. If a golf club head comes loose during a
swing, it flies off on a path (2) ____________ to the circle at its point of release. In uniform circular motion, the direction of
the centripetal force is always (3) ____________ to that of the instantaneous velocity. The acceleration is always directed
toward the (4) ____________ for an object moving in uniform circular motion. The (5) ____________ of a satellite provides
the centripetal force that causes the satellite to move in a curved path. The orbital velocity of a satellite is independent of the
satellites (6)____________ . The time necessary for an object moving with simple harmonic motion to complete one back and
forth motion is called its (7)____________ . The (8) ____________ of vibration is the distance from the objects rest position
to the point of greatest displacement.
Problems
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1.
An amusement ride consists of a turntable of 2.0 m radius turning at 0.70 revs/s about a vertical axis. If a 70.0 kg
child sits at the outer edge of the turntable, what force is necessary to keep the child from sliding off?
(2.7 x 103 N)
2. A vehicle, with a mass of 800 kg, turns an unbanked corner, with a radius of 52.0m, at a speed of 20.8 m/s.
a. Calculate the coefficient of friction for this turn. (0.848)
b. If the turn is a semi-circle (half a circle), calculate the time it takes to go around the turn. (7.85 s)
3. A 12 g stopper is swung in a horizontal circle with a 1.5 m long string, at a speed of 25 m/s when the string
breaks.
a. Calculate the tension in the string when it broke. (5.0 N)
b. If the same stopper and string had been swung in a vertical circle, what is the maximum speed that could have
been reached? (24.7 m/s)
4. An amusement ride spins in a vertical loop. It takes 4.80 seconds to complete one loop. The a 50 kg rider will feel
as if her mass has increased to 150 kg at the bottom of the loop.
a. Calculate the radius of the loop. (11.5 m)
b. Calculate the speed of the ride. (15.0 m/s)
c. What apparent weight would this rider have at the top of the circle? (488 N)
5. A satellite orbits Earth 20 000 km above the surface.
a. How fast is the satellite moving? (3.89 x 103 m/s)
b. How many hours does it take to circumnavigate (go around) Earth? (9.45)
Work Fill in the Blanks
Work is the result of a (A) ____________ applied over a (B)____________ . These two quantities must be in the same
direction. The equation is W = (C) ____________ . If a force is applied at an angle, then only the component of force (D)
____________ direction does the work. We must use trigonometry to calculate the magnitude of the force doing the work.
Recall SOH, CAH, TOA. Friction is a force that acts in the (E) ____________ direction of motion, and the formula to find the
force of friction is: (F)____________ . Work is the transfer of (G)____________ . This can result in an object being higher
than before thus the object gains (H)____________ . The rate at which work is done is called (I)____________ . It is
measured in Joules per second or (J)____________ . The two formulas for this are P = (K) ____________ and
(L)____________ . Work is being done if there is a change in (M) ____________ or a change in speed or to overcome
(N)____________
Energy
The Law of (A) ____________ of energy states that (B)____________ . In a closed system the total amount of
energy remains (C)____________ . Objects in motion have (D) ____________ energy. The formula is : (E)____________
Objects that have stored energy are said to have (F)____________ energy. We usually deal with gravitational potential
energy. The formula is :(G)____________ Energy can be used to do work. The amount of work that can be done is
(H)____________ to the total energy of the object. When a rollercoaster car rolls up a hill, (J)____________ energy is
converted to (K)____________ thus a change in elevation. A pendulum released from any height gains (L)____________
energy and loses (M)____________.
Problems
1. A force of 30 N is applied along the handle of a wagon, which makes a 20˚ angle to the ground. How much work is
done in pulling the wagon 50 m? (1.4 x 103 J)
2. What is the power output of a crane that lifts twenty (20) 1000 kg steel girders to a height of 30 m in 2.0 min?
(4.91 x 104 W)
3. A force of 30 N accelerates a 2.0 kg object from rest for a distance of 3.0 m along a frictionless, level floor. The force
changes to 15 N for an additional distance of 2.0 m.
4. What is the final kinetic energy of the object? (1.2 x 102 J)
a) How fast is the object moving at the end? (11 m/s)
5. A 2.00 g bullet is fired into a tree stump. It enters at a speed of 300 m/s and comes to rest after having penetrated
5.00 cm in a straight line.
a) What was the change in the bullets kinetic energy? (90.0 J)
b) How much work did the tree do on the bullet? (90.0 J)
c) What was the average force during impact? (1.8 x 103 N)
6. If a 2000 kg car is travelling at a speed of 20.0 m/s when it hits a cement wall and it stops within 3.00 m, how large
was the average retarding force? (1.33 x 105 N)
7. A sled has a mass of 2.80 kg and contains a child with a mass of 30.0 kg. If the sled is pulled for a distance of 300 m
by a rope that makes an angle of 52.0˚ with horizontal, and a force of 100 N is applied along the rope, how much work
is done on the sled and child? (1.85 x 104 J)
8. A horse pulls a 200 kg sleigh across a field that is 300 m long. The reins make an angle of 30.0˚ with the horizontal,
the coefficient of friction is 0.325 and the horse and sled travel at a constant velocity of 3.00 m/s. What is the force
the horse applies along the reins? (736 N)
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9.
The following graph shows the force applied by a plow being pulled across a field. Calculate the total work done.
(5000 J)
0
SHM
1.
50
100
150
200
250
300
6.
A vertical spring has a 2.87 kg mass placed on it. The spring stretches 5.73 cm. What is the spring constant?
(491 N/m)
A 87.5 g mass replaces the 2.87 kg mass in the above question. How many centimeters does the spring stretch?
(0.175 cm)
A horizontal spring (k = 200 N/m) has a 0.650 kg mass attached to it. The spring is stretched 14.8 cm. What will be
the maximum speed of the mass? (2.60 m/s)
A horizontal spring (k = 120 N/m) has a 0.320 kg mass attached to it. The spring is stretched 14.8 cm. What will be
the speed of the mass when the mass is 2.33 cm from the equilibrium? (2.83 m/s)
A horizontal spring has a 34.7 g mass attached on it. When it is compressed to a maximum of 12.0 cm and then
released it is noticed that the mass is moving with a speed of 3.00 m/s when it is 5.06 cm from the equilibrium.
Calculate the spring constant. (26.4 N/m)
What is the speed of the mass at point A? (13 m/s)
7.
What is the speed of the mass at point B? (2.1 m/s)
2.
3.
4.
5.
25 cm
1200
A
B
Waves
Fill in the lettered blanks.
A ____________ waves require a material medium for energy transfer. A(n) B ____________ wave causes the
particles of the medium to vibrate in a direction in which the wave is travelling. C ____________ waves need no
medium for travel. A(n) D ____________ is a single disturbance traveling through a medium. The E
____________ of a wave is the number of waves that pass a point per second. The F ____________ of a wave is
the reciprocal of its frequency. The G ____________ of a wave is the linear distance between any two
corresponding points on consecutive waves. H ____________ is the process involved when two waves meet and
superimpose their amplitudes. The I ____________ of a mechanical wave depends upon the medium. When
waves pass from one medium to another, their J ____________ remains unchanged. A(n) K ____________ wave
is produced when a wave train moving in one direction meets an identical wave moving in the opposite direction.
Two pulses with identical shapes but opposite displacements move toward each other in a medium. The point in
the medium that is never displaced is a (n) L____________ . M ____________ is the direction change of waves
at the boundary between different media. N ____________ is the bending of a wave around an obstacle. O
____________ are undisturbed areas that are formed when two sets of waves interact with one another. The P
____________ is a line perpendicular to a barrier at the point where an incident ray strikes the barrier. When a
wave is reflected from a barrier, the angle of Q ____________ equals the angle of reflection. Waves provide a
means of transferring R____________ .
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Problems
1. What is the wavelength of a sound emitted by a tuning fork of frequency 440 vibrations per second? The speed of
sound is 332 m/s at 0.0˚C and increases 0.60 m/s for each degree temperature rise. The tuning fork is at 32˚C. (0.80
m)
2. Radio waves travel at the speed of light, 3.00 x 108 m/s. What is the wavelength of a radio wave from an AM station
broadcasting at a frequency of 750 kHz. (400 m)
3. A standing wave in clothesline has 4 nodes and 3 antinodes. The clothesline is 12 m long and is vibrating at 0.50
vibrations per second. What is the speed of the wave? (4.0 m/s)
4. A beam of light strikes a mirror at an angle of 43˚. What is the angle of reflection?
5. A light wave is reflected off the surface of a newly found planet. The light wave returns 2.34 s after it is sent.
Determine the distance between the Earth and this new planet. (3.51 x 108 m).
6. A train is moving at a speed of 32 m/s toward a stationary observer with its whistle (1.85 x 103 Hz) sounding. If the
speed of sound in air 341 m/s, what is the apparent frequency as heard by the observer? (2.04 x 103 Hz)
7. A 2.20 x 103 Hz whistle is moving away from you. The apparent frequency you hear is 2.08 x 103 Hz and the speed of
sound is 340 m/s. What is the speed of the whistle?
Answers kinematics
scalar 2. vector 3. vector 4. directions 5. magnitude 6. tail 7. resultant 8. displacement 9. velocity
acceleration 11. average 12. instantaneous 13. acceleration 14. m/s2 15. negative 16. time
9.81 m/s2 18. Uniform
Answers kinematics graphs
constant 2. slope 3. velocity 4. constant 5. increases 6. zero 7. velocity 8. position 9. acceleration
square of the time 11. acceleration 12. opposite 13. acceleration
Answers vectors and projectiles
1. vector 2. vector 3. added 4. direction 5. resultant 6. opposite 7. Pythagorean 8. Concurrent 9. 21
equilibrium 11. projectile 12. independent 13. horizontal 14. vertical 15. Height
Answers to forces
Newton 2. force 3. Kinematics 4. Dynamics 5. Inertia 6. external force 7. accelerated 8. Newton *N* 9. mass 10.
Weight 11. Mass 12. Friction 13. normal 14. equal and opposite force
Answers to gravitation
Kepler 2. ellipses 3. radius 4. Newton 5. directly 6. inversely 7. law of universal gravitation 8. Weight
9. acceleration
Answers to circular motion
centripetal 2. tangent 3. perpendicular 4. centre 5. weight 6. mass 7. period 8. amplitude
Answers to work
1.
A. force B. distance C. F x d D. in the same E. opposite F. Ff = uFn G. energy H. potential I.
power J. Watts K. Work/time L. Force x vel M. height N. friction
Answers to energy
2.
A. conservation B. the total energy in a system can not increase or decrease C. constant D. kinetic
E. Ek = 0.5mv2 F. potential G. Ep = mgh H. equal J. kinetic K. potential L. kinetic M. potential
Answers to waves
A. mechanical B. longitudinal C. Electromagnetic D. pulse E. frequency F. period G. wavelength
H. interference I. speed J. frequency K. standing L. node M. Refraction N. Diffraction O. Nodal lines P.
normal Q. incidence R. energy
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