Intro to Physics Questions
I have taught courses in
Introductory Physics at Antelope Valley College in
Lancaster, CA and Cleveland Chiropractic College in Hollywood, CA. These are
the study questions I give my students and are supplementary to the questions
in the textbook. Feel free to use them in any way you wish. I will update this
area as time permits. The answers will follow a couple of weeks after the
questions are posted.
One note: Because of the
limitations of web publishing, we use "E" to indicate
a number being multiplied by the specified power of ten. For instance, 3.5 E-3
means 3.5 times ten to the -3 power.
Physics 1 --- Chapter 1 Study Sheet
1) A snail can travel at
a rate of 2.3 inches per minute. At the same rate, how
many miles will it travel in a year?
2) Convert 3.675 E5 Mg into ng.
3) A rectangular block of
Beryllium is measured and found to be 2.48 cm wide,
5.77 cm long, and 1.8 cm tall. What is its volume in cubic meters?
4) A right triangle has a
68° angle. The adjacent side to that angle measures
16 meters. What is the area of the triangle?
5) How many significant figures do the following have?
d) 3.400 E-8
6) Convert these decimal numbers to scientific notation:
7) Convert these scientific notational numbers to decimal numbers:
a) 4.508 E-5
b) 6.88 E11
c) 3.81 E-1
d) 4 E2
8) Give x and y coordinates for the following points given in polar coordinates:
a) (54 , 30°)
b) (600 , 45°)
c) (87.5 , 18°)
9) Give r and theta for the following points given in rectangular coordinates:
a) (3 , 4)
b) (12 , 24)
c) (9.25 , 2.75)
10) Planet X is known to
have a mass of 2.85 E24 kg. Assuming it is a perfect
sphere in shape, and its diameter is 5.59 E6 m, calculate its density.
11) The mass of the sun is
2 E30 kg, and the mass of the Hydrogen atom, of
which the sun is mainly composed, is 1.67 E-27 kg. How many Hydrogen atoms
are in the sun?
12) The basic function of
an automobile carburetor is to atomize the gasoline
and mix it with air to promote rapid combustion. Assume that 50 cubic cm of
gasoline is atomized into N spherical particles, each with a radius of 2.0 E-5 m.
What is the total surface area of these N spherical droplets?
13) The speed of light is
3.00 E8 m/s. If the distance from the sun to the Earth is
93,000,000 miles, how long does it take for light to arrive here from the sun?
(One mile = 1609.344 m)
14) The Andromeda galaxy
is about 2 E6 light years distant. The snail in problem
#1 would take how long to get there if it were able to do so?
15) How many nanojoules are in one kilojoule?
16) A cement truck is pouring
cement for a patio at a rate of 25 cubic yards of
cement per hour. Express that in cubic feet per minute.
17) Using a diagram, describe the difference between accuracy and precision.
18) A 30°-60°-90°
triangle has a hypotenuse of 24 meters. How long is the side
opposite the 60° angle?
19) Derive the expression (sin x)^2 + (cos x)^2 = 1.
20) If sin q = 8/17, find cos q.
21) The road leading from
Halloran Summit to Las Vegas is 83 miles long. If we
assume that the road is a straight line and the overall downgrade is .35°, calculate
the overall descent, in feet, between the two points.
22) A benevolent wizard pops
into your life one day and tells you he will give you
a billion dollars if you can spend all of it during your lifetime at a rate of exactly
one dollar every second. Do you get the moolah?
23) Two points are given
in polar coordinates as (3 , 30°) and (6 , 150°). What is
the distance between the two points?
24) Most major league pitchers
throw a fastball having a velocity of 90 miles per hour.
Assuming that the distance from the pitcher to the hitter is 60 feet, how long does the
batter have to react once the ball has left the pitcher's hand?
25) A certain west coast
beach is 3000 meters long, 30 meters wide, and 4 meters
deep. If grains of sand are perfect cubes and measure .25 mm on a side, how many
grains of sand are there in the beach?
Physics 1 --- Chapter 2 Study Sheet
1) A recent car commercial
states that its latest automobile can go from zero to
60 miles per hour in 7.5 seconds. What is its acceleration in SI units?
2) A ride at Magic Mountain
plummets riders straight down from a height of ten
stories. Given that the average story is twelve feet high, how fast is the ride going
when it reaches the ground, in SI units. (3.281 ft = 1 m)
3) Billy is riding his bicycle
down a crowded boulevard at 25 miles per hour. All of
a sudden a large garbage truck backs out into his way, some 70 feet ahead of him.
What must his deceleration be, again in SI units, so that Billy and his bike do not
become part of the truck? Assume Billy hits his brakes immediately after seeing
4) The AV College ladies
softball team is having a workout in the park. Heather
can run all around the bases (60 ft apart) and touch home again in 16.6 s. What is
her displacement? What is her average speed? What is her average velocity?
5) One of the girls hits
a long home run and the ball gets stuck, some 10.5 m up
in a tree. One of her teammates thinks she can throw another ball up at it to knock
it down. What is the minimum velocity necessary for the thrown ball to displace the
ball stuck in the tree (assuming a touch is all it needs)?
6) A skateboard, accelerating
from rest at a constant rate, experiences a
displacement of 44 m in 20 s. What is its acceleration?
7) A bowling ball is released
at rest from the top of the Washington Monument.
It hits the ground after falling for 6.0 s. Assuming air resistance is negligible,
what was the height from which the ball was dropped?
8) Planet Dirtbag is known
to have gravity just two-fifths that of Earth's. If a
Dirtbaggian hulaball is projected vertically from the ground at a velocity of 63.7 m/s,
how long will take take for the hulaball to touch the surface of the planet?
9) When a certain dragster
reaches a velocity of 80 m/s, it begins a negative
acceleration by releasing a drag chute and applying its brakes. While reducing its
velocity back to zero, its acceleration is a constant -7.5 m/s/s. What displacement
does it undergo during this deceleration period?
10) A rock is thrown downward
from the top of a tower with an initial velocity
of 14 m/s. If the rock hits the ground after 3.0 s, what is the height of the tower?
11) Michael Johnson set a
world record in the 1996 Olympics by running the 200
meter dash in 19.32. How fast was his average speed in SI units? How fast is this
in miles per hour?
12) Human reaction time averages about .18 s. That benevolent wizard reappears
in your life again and tells you he will hold a thousand dollar bill just above your open
thumb and forefinger and will drop it any moment. The length of the bill is 15.5 cm.
If your reactions are average, will you catch the money or let it slip thru your fingers?
Assume the bill falls straight down without any air resistance.
13) The distance from the
Earth to the sun is 93,000,000 miles. Find the velocity
of the Earth in its orbit about the sun.
14) A railroad train travels
from point A to point B at a rate of 80 miles per hour and
returns by the same route at 100 miles per hour. What is its average velocity for
the round trip?
15) Two men, each holding
a baseball, stand at the top of a building. Each man
throws their baseball at a speed of 16 m/s, one straight up and one straight down.
The first one hits the street in a time t1. How much later is it for the second ball
to hit the street (in terms of t1)?
16) Construct a displacement-time graph with the following specifications:
From t=0 to t=2 s, the body travels at a constant 2 m/s
b) From t=2 to t=4 s, the body remains motionless
c) From t=4 to t=7 s, the body travels at a constant 1 m/s
d) From t=7 to t=9 s, the body travels at a constant -3 m/s
e) From t=9 to t=10 s, the body remains motionless
What is the final displacement of the body from its starting position?
What is its average velocity?
17) Observe the following graph and describe the motion during each interval:
(The graph did not translate into HTML code...sorry)
18) A crazed physics teacher
jumps out of an airplane and accelerates with gravity
to a maximum velocity of 58.8 m/s in 6 s. He then opens his parachute and after a
four second deceleration, descends at 10 m/s for 60 seconds, reaching the ground.
From what height did the crazed physics teacher jump?
Physics 1 --- Chapter 3 Study Sheet
1) Explain the difference between a vector and a scalar and gives three examples of each.
2) Derive the equation: sin squared theta + cos squared theta = 1.
3) Explain what arithmetic
combinations of scalars, vectors, and constants are
allowable and what their resultants are.
4) A man is taking his pregnant
wife to the hospital to deliver a baby. They live
14.0 km south and 11.5 km east of the hospital. If they travel unimpeded at a
constant speed of 25 m/s, how much time would they save by traveling in a direct
diagonal line than by rectangular streets as they had to?
5) Add these two force vectors analytically: F1 = (16 N, 50°) + F2 = (12 N, 190°).
6) An ant on a picnic table
walks 30 cm eastward, then 25 cm northward,
then 10 cm westward. What is the magnitude and direction of the net
displacement from his starting point?
7) Three men combine to exert
370 N at an angle of 15° above horizontal as
they push their broken down 1964 Impala (you know, the one with grey lights
in the wheel wells, the dingle balls and the tuck-and-roll interior) to a service
garage. What are the parallel and perpendicular components of their combined
force relative to the ground?
8) Five dung beetles are
fighting over a dungball and are pushing with an equal
force but in different directions. They push in these five directions: north,
northeast, southwest, east, and northwest. What direction will the ball go?
9) Raul Mondesi throws a
baseball from deep right field all the way to third base
on the fly. The ball is thrown at an initial velocity of 32 m/s and at an initial angle
of 27° with respect to the horizontal. If the ball is caught by Todd Zeile at third at
the same height as where it was thrown, and the ball is in flight exactly 3.0 seconds,
how far did Raul throw the ball, that is, what is the ball's horizontal displacement?
10) A big game hunter is
out on safari in the deepest jungles of Zimbabwe.
He spots his prey, a spotted ginger monkey, 30 m above him in a tree which stands
20 m away from. He knows that the exact instant he fires his rifle, the monkey will
drop from his perch and fall to the ground to avoid being hit by the bullet. How far,
above or below the monkey, must the hunter aim, in order to hit the monkey?
11) An NFL quarterback wants
to throw a football to a wide receiver 30.0 m down
the field. If he knows he throws at an initial velocity of 18.0 m/s, at what angle must
he throw the ball in order to get the receiver the ball?
12) A rescue helicopter is dropping supplies to a band of stranded explorers. If the
helicopter is 150 m above the ground and travels at a constant velocity of 40 m/s,
how far ahead of the explorers must the care package be dropped to land at their position?
13) A stone is thrown at
an angle of 30° above the horizontal with an initial speed
of 12 m/s from the top edge of a cliff whose height is 120 m. What is the magnitude
of the horizontal and vertical components of the stone's velocity the instant it hits the ground?
14) No one has ever long
jumped a distance of 30 feet. Given that the absolute top
speed that a man can run is 25 miles per hour, find the angle at which he needs to
jump, relative to the horizontal, to long jump 30 feet.
15) Dan Marino takes the
ball at the line of scrimmage, runs backward for 10 yards,
then sideways, parallel to the line of scrimmage for 15 yards. Then he throws a 40 yard
forward pass straight downfield, perpendicular to the line of scrimmage, where his receiver
is tackled immediately. How far has the football been displaced from its original position?
16) To qualify with the M-16
rifle in the US Army, a soldier must be able to hit targets
at 300 yards away. A soldier aims directly at the bullseye but finds that the bullet hits
4 inches below the bullseye. What is the bullet's initial velocity? (Here ignore air
resistance though it is a real factor.)
17) A two-sided drawbridge
malfunctions in front of your car and leaves a gap of
12 m in between the two spans of the bridge. If the spans are elevated 22° relative
to the horizontal, what must your car's minimum velocity be to be able to safely
land on the opposite span of the bridge?
18) The highest mountain
on Mars is Olympus Mons, rising 22,000 meters above
the Martian surface. If we were to throw an object horizontally off the mountain top,
how far away, diagonally, from the point of throwing on the mountain top would the
object land. The gravity on Mars is .38g.
19) Mickey Mantle hits a
baseball with a speed of 44 m/s and at an angle of 30° above
the horizontal. A 5 m high fence is located at a horizontal distance of 132 m from the
point where the ball is struck. Assuming the ball leaves his bat 1 m above the ground,
find how much distance the ball clears the fence by.
20) It is a common tale about
George Washington that he was able to throw a silver
dollar across the Potomac River. Assuming that the river is 75 m wide, and he threw
the dollar at a 45° angle, find the minimum initial speed necessary to throw the coin
across the river.
Physics 1 --- Chapter 4 Study Sheet
1) Explain the difference between mass and weight.
2) State Newton's three laws of motion and give an example of each.
3) Explain the two general types of frictional forces and how they are applied.
4) Explain the difference
between classical (Newtonian) and relativistic (Einsteinian)
5) A block of wood of mass
40 kg is acted upon by a constant force of 12 N.
How fast will the block be moving after three seconds?
6) The acceleration due to
gravity on planet Barf is 3.5 times what it is on planet
Earth. Thus an object of mass 22 kg on Earth would have what mass on planet Barf?
7) The acceleration due to
gravity on planet Drek is 1.7 times what it is on planet
Earth. Thus an object of mass 160 kg on Drek would have what weight on planet Earth?
8) A wagon of weight 300
N is accelerated across a level surface at .5 m/s/s.
What net force acts on the wagon?
9) An elevator weighing 30000
N is supported by four identical steel cables.
What is the tension in each cable when the elevator is being accelerated upward
at a rate of 2.5 m/s/s?
10) A horizontal force of
650 N is needed to overcome the force of static friction
between a level floor and a 220 kg crate. What is the coefficient of static friction
between the wooden crate and the concrete floor?
11) A sailboat with mass
2500 kg experiences an eastward force of 4500 N by the
ocean tide and a wind force against the sails with magnitude of 5500 N directed
toward the northwest, i.e., 45° north of west. What is the resulting acceleration in
both magnitude and direction?
12) A full boxcar of mass
240 tons at rest becomes uncoupled from the train on a
12° slope. If the track is considered to be frictionless (hardly possible of course),
what velocity does the boxcar have after 8.0 seconds?
13) You are driving your
car to school one day when you have to brake suddenly.
If you are traveling at a rate of 35 m/s, your car has a mass of 1800 kg, and your
braking force is a constant 8000 N, how far does your car travel before coming
to a complete stop?
14) Mark McGwire strikes an incoming 42 m/s fastball. The ball leaves the bat at
54 m/s after a ball-on-bat contact time of .03 s. What force is exerted on the .15
15) Kristi Yamaguchi moves
on the ice at 12 m/s and coasts to a halt in 140m
on a smooth, level ice surface. What is the coefficient of friction between the
ice and the skates?
16) Thelma and Louise are
using a rope to pull a safe out of a bank that weighs
1200 N across a level surface with constant velocity. The rope makes a 20° angle
above the horizontal and the tension in the rope is 250 N. What is the coefficient
17) A 30 kg traffic light
hangs midway between two poles 50 m apart. If the sag in
the cable is .75 m, what is the tension in each side of the cable?
18) You drive to San Francisco
and park your car in front of your friend's house on a
rather inclined street. You know that the coefficient of friction between your tires
and the street is m = .78. What is the steepest angle, q, that you can park your car
(wheels locked) without it slipping downhill?
19) Ingemar Stenmark was
skiing at 22 m/s down a 30° snow slope, when he
encountered a large patch of wet snow. The wet snow had a coefficient of friction
of m = .67. How far down the hill did he go before coming to a halt?
20) A 150 N sled is pulled
up a 28° slope at a constant speed by a force of 100N.
Near the top of the incline, the sled is released. With what acceleration does the
sled go back down the hill?
Physics 1 --- Chapter 5 Study Sheet
1) Describe the relationship
between work, energy, and power; show the equivalence
of the units of W=Fd cos q and KE = 1/2 mv2.
2) Give three examples of potential energy and the ways it is converted into kinetic energy.
3) Describe the difference between conservative and non-conservative forces.
4) Describe Hooke's Law and its relation to potential energy stored in a spring.
5) Robin Hood shoots an arrow
straight up at an initial velocity of 65 m/s. Using energy
considerations only and neglecting air resistance, find the maximum height of the arrow.
6) What is the minimum amount
of energy required for an 80 kg climber carrying a 20 kg
pack to climb Mt. Everest, a peak 8850 m high?
7) A 60 N crate is pulled
up a 7 m inclined plane at a constant velocity. If the plane is
inclined at an angle of 25° to the horizontal and there exists a constant force of friction
of 8 N between the crate and the surface, what is the net gain in potential energy by the
crate in the process?
8) What is the kinetic energy of a 5 oz. baseball thrown at 90 miles per hour?
9) A pile driver drives a
3500 kg post through a height of 6.5 m on each stroke. If the
resisting force of the ground is 3.5 x 106 N, how far into the earth is the huge post
driven on each stroke?
10) A 55 kg woman runs up
the Empire State Building stairs, a vertical rise of 320 m,
in 9.5 minutes. How much work did she do? What average power did she supply?
11) A simple pedulum, 1.2
m in length, is released from rest when the support string
is at an angle of 38° from the vertical. What is the speed of the suspended mass at the
bottom of the swing?
12) Another simple pendulum,
one of 1.8 m in length, is released with a push downward
when the support string is at an angle of 27° from the vertical. If the initial push gives it
an initial speed of 1.4 m/s at the release point, to what maximum angle will it move in the
second half of its swing?
13) The work done by static
friction is always: A) positive B) negative C) zero D) against the
direction of motion E) along the surface
14) You smack a tennis ball against a wall and notice that the ball only has 3/4 of its original
speed when it bounces back. What part of its kinetic energy did it lose during its collision
with the wall?
15) You and your friends
exert a force of 3500 N at an angle of 12° to the horizontal
pushing your broken down primer gray 1964 Impala with dingle balls, tuck and roll
interior, twice pipes, grey lights in the wheel wells, and "Crystal Blue Persuasion"
painted on the rear glass. The car has mass of 1500 kg. You achieve an acceleration of
1.7 m/s/s over a distance of 10 meters. What force of friction acts to retard the motion
of the car? How much work is done by you and your friends?
16) You ride your bicycle
down a hill. Your total mass is 54 kg. At the top of the hill, your
speed is 5 m/s. The hill is 18 m high and 165 m long. If the force of friction is 20 N, what is
your speed at the bottom of the hill?
17) The Old Faithful geyser
in Yellowstone Park shoots water to a height of 40 m nearly
every hour. At what velocity must the water leave the ground?
18) Grossbarger T. Zyglewicz,
a polish weightlifter, can lift 250 kg to a height of 2 meters
in 1.75 seconds. How much work does he do and what is his power output?
19) Last time you went water
skiing you noticed that the speedboat required 85 kW to
move at a constant speed of 18 m/s. What is the resistive force of the water at that speed?
20) Brett Butler throws a
.15 kg baseball at a speed of 40 m/s and at initial angle of 22°
from a height of 2 m. What are the kinetic and potential energies of the ball at the
highest point in its trajectory?
21) My MR2 sportscar has
a mass of 1120 kg and accelerates from zero to 25 m/s in 7.8 s.
What is the average horsepower delivered by the engine? (1 hp = 746 W)
22) A spring platform is
constructed for a stunt man to use for simulating the results
of a nearby explosion. If the spring is compressed a distance of .375 m, it can launch
a 70 kg stunt man to a height of 6 m when released vertically from rest. Neglecting all
of the resistive forces, determine the spring constant and the speed of the stunt man
as he passes the equilibrium position (x = 0) of the spring.
Physics 1 --- Chapter 6 Study Sheet
1) Describe the relationship between force, momentum, time, mass and velocity.
2) Describe the principle
of conservation of momentum; describe how it applies to
two-dimensional motion as well as linear motion.
3) Describe the difference
between elastic and perfectly inelastic collisions and give
an example of each.
4) A 55 kg roller skater
accelerates from rest to a speed of 18 m/s in 4.0 s. What is her
change in momentum? What force must have been applied? Verify your answer using
principles of mechanics.
5) A swimmer jumps horizontally
off an aluminum skiff (small boat) of mass 175 kg. The
swimmer's speed immediately after leaving the skiff is 3.2 m/s. If the skiff moves at a
speed of 1.25 m/s, what is the mass of the swimmer?
6) A 4800 kg bus moving at
28 m/s rams into a parked car and locks bumpers as the
two vehicles continue down the road at 19 m/s. What is the mass of the parked car?
7) A 65 g racquetball, initially
moving horizontally at 47 m/s, slams into the wall and
rebounds at a speed of 39 m/s. What is its change in momentum?
8) An army howitzer of mass
3200 kg fires a 70 kg shell with a velocity of 220 m/s at an
angle of 40° above the horizontal. Given that the howitzer rides on frictionless wheels,
what is the recoil velocity of the howitzer along the level ground on which it sits?
9) A machine gun is attached
to a railroad flat car of mass 1.45 x 105 kg which is able
to roll with negligible friction. How many bullets of mass 16 g must be fired at 330 m/s
off the back by the gun so that the railcar achieves a forward speed of 1.0 m/s?
10) Roger Clemens throws
a 150 g baseball at Junior Griffey at a speed of 42 m/s. The
batter hits the ball straight back at the pitcher with a return speed of 58 m/s. If the bat
is in contact with the ball for .045 s, what is the impulse experienced by the ball?
11) A pendulum bob of mass
50 g is suspended from a string 1.4 m long at an angle of
28° from the vertical. If the pendulum is released from rest and strikes an 80 g ice
puck at the lowest point in its swing, what will the speed of the ice puck be if all of the
pendulum's momentum is transferred to the puck?
12) A loaded freight train of mass 45,000 kg is coasting at a constant speed of 2.2
m/s along a horizontal track. It collides and couples with an empty, motionless railcar
of mass 20,000 kg. What percentage of the initial kinetic energy of the larger train is
retained by it after the collision?
13) If the momentum of an
object is raised by a factor of nine, by what factor is its
kinetic energy changed?
14) If the kinetic energy of an object is cut by 50%, how does its momentum change?
15) A 3 kg ball traveling
eastward at 6 m/s collides elastically with a 4 kg ball traveling
westward at 3 m/s. What are the final velocities of the balls after the collision?
16) A billiard ball traveling
at 1.4 m/s strikes two identical balls such that one ball rolls
off at 40° relative to the direction of the striking ball, and the other rolls of at -50°. Given
that the striking ball is motionless after the collision, what is the ratio of the speeds of
the first struck ball to the second struck ball after the collision?
17) A 7.4 kg bowling ball
strikes a 1.8 kg bowling pin. The pin flies forward at a velocity
of 6.2 m/s while the ball continues forward with a velocity of 3.9 m/s. What was the
bowling ball's original velocity?
18) A billiard ball moving
at 2.7 m/s strikes a stationary ball of the same mass. After the
collision, the original ball moves forward at a velocity of 2.1 m/s at an angle of 34°
relative to its orginal motion. Find the velocity and direction of the struck ball after the
19) Emmitt Smith, mass 105
kg, is running north at 11 m/s. He is tackled in an inelastic
collision by Refrigerator Perry, mass 155 kg, running south at 4 m/s. What is the final
velocity of the two players just after the tackle?
20) A 10 g bullet is fired
into a 200 g block of wood at rest on a horizontal surface. After
impact the block slides 8.0 m before coming to rest. If the coefficient of friction is
m = 0.4, find the speed of the bullet before impact.
Physics 1 --- Chapter 7 Study Sheet
1) Explain the relationship
between arc length, angular displacement, and the radius in
circular motion. Convert radians to degrees and vice-versa.
2) Explain the derivation of angular velocity and its relation to linear (or tangential) velocity.
3) Explain the derivation of tangential acceleration and its relation to linear acceleration.
4) Explain the vectorial
properties of centripetal force, centripetal acceleration, tangential
acceleration, and linear velocity.
5) Describe Newton's Law of Universal Gravitation in both symbols and words.
6) State and describe Kepler's three laws of planetary motion.
7) A helicopter has rotor
blades 3.5 m long and rotating at 650 rpm. What is the tangential
velocity of each blade tip and what is the centripetal acceleration that must act 2.2 m from
the axis of rotation?
8) A 650 g mass, attached
at the end of a 83 cm string, is whirled around in a circular
horizontal path. If the maximum tension the string can withstand is 480 N, what is the
maximum velocity the mass can have if the string is not to break?
9) A .180 m radius grinding
wheel, starting at rest, develops an angular velocity of 12.5
rad/s in a time interval of 3.65 s. What is the centripetal acceleration of a point .116 m from
the center when the wheel is moving at an angular velocity of 12.5 rad/s?
10) A Ferris wheel, rotating
initially with an angular velocity of .58 rad/s, accelerates over
an 8.3 second interval at a rate of .047 rad/s/s. What is its angular velocity after this time
interval and what angular displacement (in radians and degrees) does the Ferris wheel
undergo in the 8.3 s?
11) A 35.0 kg bowling ball
is transported to the surface of planet X where it is found to have
a weight of 1450 N. The radius of the planet is known to be 4.55 x 10E6 m. What is the mass
of planet X? (G = 6.67 x 10-11 N·m2/kg2)
12) What is the angular velocity
about the center of the Earth for a person standing on the
13) If the diameter of the Earth is 7827 miles, calculate the linear speed due to the Earth's
rotation for a person standing at the equator of the Earth.
14) The cord of a weed whacker
is .18 m in length. If the motor rotates at 24 rev/s, what is the
tangential velocity of the end of the cord?