Physics Final
If you are traveling at an average speed of 60 miles per hour, how long will it take to go from mile marker 1 to mile marker 7?
6 minutes
In 1989, Ann Transom broke the U.S. women's record for a 24 h run by covering a distance of 143 miles. What was her average speed?
6 mph
Force
A push or pull
Vector
A quantity that has magnitude and direction
Inversely proportional
A relationship in which two quantities have a constant product. If one quantity increases by a certain factor, the other decreases by the same factor.
Proportional
A relationship in which two quantities have a constant ratio. If one quantity increases by a certain factor, the other increases by the same factor
Why is acceleration a vector?
Acceleration is the rate of change of velocity, which is itself a vector.
A figure skater is spinning with her arms extended. she pulls her arms close to her body. What happens?
Her rotational inertia decreases
Which statement is true about Newton's first law of motion?
It was an addition to and improvement of Galileo's observations.
If you travel north for a mile and then south for a mile, what is true about your average speed?
It will be a lot greater than the magnitude of your average velocity.
A possible form of the proper metric unit for momentum is...
N*sec
If a moving object hits a still object, what happens to the momentum of the moving object?
The momentum of the moving object is decreased by the amount of momentum the stationary object picks up at the time of the collision.
Newton's First law of motion
The velocity of an object remains constant unless an unbalanced force acts on the object
The Earth, which orbits the Sun in an elliptical path, reaches its closest point to the Sun on about January 4 each year. Will the work done by the gravitational force of the Sun on the Earth be positive, negative, or zero over the next 6 months? Will the work done be positive, negative, or zero over the next year?
The work done will be negative The work done will be zero
conserved
This term is used in physics to mean that a number associated with a physical property does not change over time
Torque equation
Torque=radius*(force perpendicular to the radius)
Your instructor rides on a merry go round turning at a constant rate. In which direction does the net force on your instructor point?
Toward the center
Translational (linear) speed is displacement divided by time, and rotational speed is what?
angular displacement divided by time
A torque acting on a body tends to produce
angular rotation
Newton's third law only applies to
any pair of objects that exert forces on one another
How do we calculate centripetal acceleration?
by subtracting two velocity vectors separated by a short time interval
Time equation
distance / speed
The average speed of an object is defined to be the
distance it travels divided by the time it takes.
If the net force on an object is directed due west, which way docs the acceleration point?
due west
conservation of angular momentum
if the net external torque on a system is zero, the total angular momentum of the system does not change
What is not a vector quantity?
mass
translational motion
motion along a path
You apply a 75-N force to pull a child's wagon across the floor at a constant speed of0.5 m/s, If you increase your pull to 80 N, the wagon will
move with a continuously increasing speed
In uniform circular motion the acceleration is... ?
perpendicular to the velocity
Which of the following is an appropriate unit for describing rotational acceleration?
rev/s^2
If the mass of an object in free fall is doubled, its acceleration
stays the same.
What is weight?
the force of gravity on an object
Which of these things has an inverse-square relationship?
the intensity of sunlight and distance from the sun
If a mother weighs four times as much as her child, where should she sit to keep the seesaw level if the child is seated at the far right hand side?
one fourth of the distance from the pivot to the left end of the seesaw
What describes the "average speed" of a trip by car?
the distance traveled divided by how long it took
What is measured by the "newton?"
the force needed to accelerate a 1-kilogram mass at 1 meter per second per second
gravitational field
the gravitational force experienced by a 1-kg mass placed at a point in space
What is the "center of mass"?
the location that the object would concentrate to if we imagined it to shrink to a point
Your weight on a given planet could be calculated from which of the following?
the mass of that planet and its diameter
What else became calculable when Henry Cavendish calculated the value of G (the gravitational force between two objects on Earth)?
the mass of the earth
The angular momentum of a particle moving in a circle around a point is equal to what?
the mass times time speed of the particle times the radius of its orbit
mechanical energy
the sum of the kinetic energy and various potential energies which may include the gravitational and the elastic potential energies
How many significant figures are in 0.0380 ?
3
What are the size and direction of the force that is the sum of a force of 3 N acting south and a force of 6 N acting north?
3 N north
An astronaut on a strange planet has a mass of 80 kg and a weight of 240 N. What is the value of the acceleration due to gravity on this planet?
3 m/s2
You throw a ball straight up at 25 m/s. How many seconds elapse before it is traveling downward at 6 m/s?
3 seconds
A 1500 kg car is traveling at 20 m/s around a curve with a radius of 100 m. What is the angular momentum of the car?
3,000,000
If the wheel on a car accelerates from rest at a constant rate of 1.5 rev/s^2, how fast will it be turning after 3 s?
4.5 rev/s
A fully equipped astronaut has a mass of 140 kg. If the astronaut has a weight of 690 N standing on the surface of a planet, what is the acceleration due to gravity on this planet?
4.93 m/s^2
A 1200 kg frictionless roller coaster starts from rest at a height of 20 m. What is its kinetic energy when it goes over a hill that is 13 m high?
82.32 kJ
Express 0.0000930 in proper scientific notation. (Keep track of significant figures)
9.30 x 10^-5
If a number in powers-of-ten notation is written as just the number 10 and the exponent, what is assumed to be part of the number?
the number 1 multiplied by 10 to the exponential power
work
the product of the force along the direction of motion and the distance moved
rotational inertia
the property of an object that measures its resistance to a change in its rotational speed
power
the rate at which energy is converted from one form to another
Rotational acceleration measures what?
the rate at which rotational speed changes
The gravitational attraction of the Sun for Earth is ____ that of Earth for the Sun.
the same as
If the pole-vaulter were to land on concrete rather than on a cushion, the impulse that stops the fall would be what?
the same because impulse is the change in momentum of the object
Gravitational force between two objects formula
F = ((G)(M1)(M2))/(d^2) F = Force in N G = Gravitational Constant M1 = Mass of 1st object in kg M2 = Mass of 2nd object in kg D = distance between objects in m
Magnitude of net force equation
F = M*S F = Force M = Mass S = Speed
If the kinetic energy of an object increases, then
the speed must increase as well
terminal speed
the speed obtained in free fall when the upward force of air resistance is equal to the downward force of gravity
Kilogram
the standard international system (SI) unit of mass. A kilo gram of material weighs about 2.2 pounds on earth
Why was Bode's law never considered a law of physics?
It had no scientific basis.
What do we know about the direction of momentum?
It has the same direction as the object's velocity.
Which of the following is true of the kinetic energy of an object?
It is directly proportional to the square of its speed.
Which of these statements is true about a geosynchronous satellite?
It remains directly above a specific location on Earth's surface.
A gun is held horizontally and fired. At the same time the bullet leaves the gun's barrel an identical bullet is dropped from the same height. Which bullet will hit the ground first?
It will be a tie
A gun is held horizontally and fired. At the same time the bullet leaves the gun's barrel an identical bullet is dropped from the same height. Neglecting air resistance, which bullet will hit the ground first?
It will be a tie.
Impluse
The product of the force and the time during which it acts, F∆t. This vector quantity is equal to the change in momentum
Earth is held in its orbit by the gravitational force of the Sun. Therefore, the force that the Sun exerts on Earth is ________ that Earth exerts on the Sun.
The same as
If two identical balls have momenta that are equal in magnitude but opposite in direction, what do we know about the speeds of the two balls after the two collide?
The speeds of the two balls will always be the same.
What do momentum and impulse have in common?
They are measured in the same units
A ping-pong ball and a golf ball have approximately the same size but very different masses. Which hits the ground first if you drop them simultaneously while standing on the Moon?
They hit simultaneously.
The net horizontal force on a 52000 kg railroad boxcar is 5200 N. What is the acceleration of the boxcar?
0.1 m/s^2
a pulley of rotational inertia 7 kg m^2 receives a torque of 2.8 Nm from a physics professor. What will the angular acceleration of the body be?
0.4
A rolling ball has an initial velocity of 1.6 m/s. If the ball has a constant acceleration of -0.33 m/s2, what is its velocity after 3.6 s?
0.41 m/s
A 0.5 kg air-hockey puck is initially at rest. What will its kinetic energy be after a net force of 0.7 N acts on it for a distance of 1.1 m?
0.77 J
A woman with a mass of 60 kg climbs a set of stairs that are h = 2 m high. How much gravitational potential energy does she gain?
1176
Formula for horizontal distance from surface after fall
Vx = x/t Vx = horizontal speed x = distance from surface fell t = time to fall
To open a very heavy door, where is the best place to push the door?
at the end of the door where the doorknob is located
Average Speed
distance travled/time taken
In Aesop's fable of the tortoise and the hare, the "faster" hare loses the race to the slow and steady tortoise. During the race, which animal has the greater average speed?
the tortoise
Which of the following is the third-law force that accompanies the force that an apple exerts on a tree? It is the force that
the tree exerts on the apple
Which of the following is the third-law force that accompanies the force that an apple exerts on a tree? It is the force that __
the tree exerts on the apple.
What is the order of magnitude of a quantity?
the value of a quantity rounded to the nearest power of ten
order of magnitude
the value of quantity rounded off to the nearest power of ten
WHat are four examples of a vector
the velocity of a baseball in flight, your displacement from walking five blocks to the North, the unbalances force from two people pushing a cart in opposite directions, the force that represents your weight
Newton's first law for rotational motion states that an object will maintain its state of rotational motion unless acted on by an unbalanced (or net)...
torque
A change in the rotational velocity of an object is produced by a net ____
torque.
Your instructor rides on a merry-go-round turning at a constant rate. In which direction does the net force on your instructor point?
toward the center
In projectile Motion the acceleration is... ?
vertical and the velocity is horizontal
What can investigators use the law of conservation of momentum to determine from the details at the scene of a car accident?
whether either of the cars was over the speed limit
Moving at a constant speed, an elevator lifts a 1200 N package 10 meters in 3 seconds. During this time, the impulse delivered to the package by the elevator is...
3600 Ns up
Mass
A measure of the quantity of matter in an object. The mass determines an object's inertia. Mass is measured in kilograms
projectile motion
A type of motion that occurs near Earth's surface when the only force acting on the object is that of gravity.
Displacement
A vector quantity giving the straight-line distance and direction from an initial position to a final position.
Inertia
An object's resistance to a change in its velocity
A 2 kg ball has been thrown vertically upward. If we ignore the air resistance, what are the direction and size of the net force acting on the ball while it is traveling upward?
Direction: Down Size: 20 N
Time Taken
Distance Traveled/Average Speed
A baseball player throws a ball from left field toward home plate. Assume that you can neglect the effects of air resistance. At the instant the ball reaches its highest point, what is the direction of the ball's acceleration?
Down
A 1100 kg car has a speed of 29 m/s. If it takes 7 s to stop the car, what is the impulse and the average force acting on the car?
Impulse: 31900 Average Force: 4557.14
Weight
The force of gravitational attraction of Earth for an object
What is the correct method to subtract a vector from another vector?
Turn the arrow you are subtracting around, and then add.
What is centripetal force?
a force that seeks the center of a circle
unstable equilibrium
an equilibrium position or orientation that an object leaves after being slightly displaced
stable equilibrium
an equilibrium position or orientation to which an object returns after being slightly displaced
Einstein described science as beginning with which of the following?
defining a set of consequences for an axiom, and testing those consequences against the material world
Which force did Kepler believe moved the planets around the Sun?
magnetism
What is kinetic energy?
the energy an object has because of its motion
What information do scientists use to estimate the total mass of the Milky Way Galaxy?
the fact that all the stars in the galaxy rotate about a common point
What is the unit of work?
the joule
torque
the rotational analog of force
gravitational potential energy
the work that would be done by the force of gravity if an object fell from a particular point in space to the location assigned the value of zero, GPE = mgh
A particle has a mass of one kilogram. What is it mass in grams?
1 x 10^3 grams
What are some major conveniences of the metric system?
It is internationally accepted. It uses standard prefixes for larger and smaller amounts than the standard unit. It is the accepted system of the scientific community. It uses multiples of ten for everything, so conversions are easy.
Instantaneous Speed
The average speed over a very small time interval
What is the fastest speed in the universe?
the speed of light
If an object moves in a straight tine with a constant speed, we can conclude that
there is no unbalanced force acting on the object.
Express 0.08300 x 10^3 in proper scientific notation. (Keep track of significant figures)
8.300 x 10^1
Which of the following is true about how the planets revolve around the sun and how the Sun rotates?
The planets revolve around the Sun in the same direction that the Sun rotates.
Mass of a planet formula
((4*pi^2)/(r^3))*(G/(p^2)) G = Gravitational Constant r = Radius in Km p = orbital period in seconds
A 1100 kg car has a speed of 29 m/s. If it takes 7 s to stop the car, what is the impulse and the average force acting on the car?
0 m/s
How many revolutions are in one degree?
0.0028
A boxcar traveling at 8 m/s approaches a string of 5 identical boxcars sitting stationary on the track. The moving boxcar collides and links with the stationary cars and they all move off together along the track. What is the final speed of the cars immediately after the collision? (You may take the mass of each boxcar to be 18,537 kg.)
1.33
What is the change in velocity if a car traveling 30 m/s north slows to 20 m/s north?
10 m/s south
A ball with a weight of20 N is thrown vertically upward. What is the acceleration of the ball just as it reaches the top of its path?
10 m/s^2 downward
What is the range from the size of protons and neutrons to the size of the visible universe?
10^41
A crate has a mass of 24 kg. What applied force is required to produce an acceleration of 3 m/s2 if the frictional force is known to be 90 N?
162 N
How many significant figures are in 0.020 x 103 ?
2
A car speeds up from 45 mph to 55 mph to pass a truck. If this requires 5 s, what is the average acceleration of the car?
2 mph
Solve the following problem with the correct number of significant figures and units (3 × 10^−4 m)(6.0 × 10^9 m)
2 x 10^6 m2
A 2 kg ball is thrown straight up in the air. What is the net force acting on the ball when it reaches its maximum height? What is the ball's acceleration at this point?
20 N 10 m/s^2
A future space traveler, Skip Parsec, lands on the planet MSU3, which has the same mass as Earth but twice the radius. If Skip weighs 800 N on Earth's surface, how much does he weigh on MSU3's surface?
200 N
A net force of 80 N accelerates an 8 kg mass over a distance of 25 m. What is the work done by this net force? What is the increase in the kinetic energy of the mass? What final velocity does the mass achieve as a result?
2000 J 2000 J 22.3 m/s
A 3 kg toy car with a speed of 5 m/s collides head-on with a 2 kg car traveling in the opposite direction with a speed of 1 m/s. If the cars are locked together after the collision with a speed of 2.60 m/s, how much kinetic energy is lost?
21.6 J
A 8 kg toy car with a speed of 7 m/s collides head-on with a stationary 1 kg car. After the collision, the cars are locked together with a speed of 6.22 m/s. How much kinetic energy is lost in the collision?
21.9022 J
An astronaut weighs 900 N when measured on the surface of Earth. How large would the force of gravity on him be if he were in an Earth satellite two Earth's radii from the center of the earth?
225 N
If the force of friction on a child's wagon is 25 N, how much force must be applied to maintain a constant, nonzero velocity?
25 N
A car initially traveling westward at 20 m/s has a constant acceleration of 1 m/s2 westward. How far does the car travel in the first 10 s?
250 m
What impulse is needed to stop a 1400 kg car traveling at 18 m/s?
25200
What is the kinetic energy of an 88 kg sprinter running at 9 m/s?
3564 J
How far can a bus travel in 6 h at an average speed of 47 mph?
282 miles
how many radians are in a circle
2π or about 6.28
If the speed of a car is tripled the momentum of the car changes by a factor of
3
What is the gravitational force between two 20-kg iron balls separated by a distance of 0.9 m? (G = 6.67 x 10-11 Nm2/kg2)
3.3 x 10-8 N
Starting at 9 A.M., you hike for 3 hours at an average speed of 7 mph. You stop for lunch from noon until 3 P.M. What is your average speed over the interval from 9 A.M. to 3 P.M.?
3.5 mph
A wheel accelerates from rest to 59 rad/s at a rate of 58 rad/s^2. What is the angular displacement of the wheel?
30 rad
A compressed air potato gun, built as a project for a physics class, launches a potato directly upward at a speed of 20 m/s. Neglecting air resistance, how long will the potato be in the air? (Use acceleration due to gravity = 10 m/s2)
4 seconds
A rock is thrown off a tall cliff with a vertical speed of 25 m/s upward and a horizontal speed of 30 m/s. What will these speeds be 3 s later?
5 m/s downward and 30 m/s horizontal
Solve the following problem with the correct number of significant figures and units: (20.00 x 10^4m)/(4.0 x 10^-3s)
5.0 x 10^7 m/s
Three forces act on an object. A 2 N force acts due east and a 5 N force acts due north. If the net force on the object is zero, what is the magnitude of the third force?
5.39 N
If a space explorer with a mass of 87 kg has a weight of 460 N on a newly discovered planet, what is the acceleration due to gravity on this planet?
5.39 m/s^2
What is the change in velocity if a car is traveling 30 m/s north changes to 20 m/s south?
50 m/s south
What is the mass of a cart that has an acceleration of 4 m/s2 when a net force of 2000 N is applied to it?
500 kg
How many degrees are in a radian?
57.3
A 1800-kg car is traveling at 30 m/s around a curve with a radius of 120 m. What is the angular momentum of the car?
6,480,000 kg·m^2/s
A woman with a mass of 60 kg runs at a speed of 10 m/s and jumps onto a giant 30 kg skateboard initially at rest. What is the combined speed of the woman and the skateboard?
6.67
A certain car can accelerate from 0 to 60 mph in 7.8 s. What is the car's average acceleration in mph/s?
7.7 mph
Suppose you climb the stairs of a five story building about 12 m high and your mass is 60 kg. The gravitational potential energy you gain is about...
7056 J
You have a mass of 75 kg. How fast (in mph) would you have to run to have the same momentum as an 18-wheeler (m = 28,000 kg) rolling along at 2 mph?
746.67
A football player kicks a .58 kg football giving it a speed of 28 m/s. If the kicker was in contact with the ball for .021 s, what was the force on the football?
773 N
What centripetal acceleration is required to follow a circular path with a radius of 50 m at a speed of 20 m/s?
8 m/s2
A bowling ball rolls off the edge of a giant's table with a horizontal speed of 15 m/s. If it takes 4 s for the ball to hit the ground, what is the height of the table?
80 m
Al the astronaut has a mass of 90 kg and a weight of 900 N when he is standing on Earth's surface. What is his mass when he is in a space station orbiting Earth with a radius of three Earth Radii?
90 kg
What is the gravitational potential energy of a ball with a weight of 62 N when it is sitting on a shelf 1.5 m above the floor?
93 J
Distance Traveled
Average Speed x time taken
Which of the following is a unit of energy? A. Newton/Second B. Joule C. Newton D. Watt E. Meter
B. Joule
Average Acceleration
Change in velocity/Time taken
What kind of acceleration does the Moon experience toward Earth?
Centripetal
Which of the following is possessed by a moving object, but not by a stationary object? A. Force B. Mass C. Inertia D. Kinetic Energy E. Time
D. Kinetic Energy
Which of these statements is true?
Even at a given distance from Earth's surface, the value of g can vary slightly.
In his experiment with rolling balls down a ramp at different ramp angles, what did Galileo discover?
For any fixed ramp angle, the acceleration of a ball was always constant, regardless of its weight.
What is Newton's second law?
Force equals mass times acceleration
What was one obstacle Newton encountered in developing his theory of universal gravitation from his observation of heavenly bodies?
He had to prove that the mass of the Earth acts as if it was concentrated at the planet's center.
Which of the following is true of the rock in this figure as it falls after being dropped from a great height?
Its speed increases until it reaches a constant value, but its acceleration decreases gradually to zero.
What is the unit for kinetic energy?
Joule
How do you find the angular momentum of a spinning object?
L=(rotational inertia)*(rotational speed)
How do you find the angular momentum of an object orbiting a point?
L=mass*velocity*(radius of path)
Which of the following statements is true about any collision between two objects with no net applied force acting?
Momentum is always conserved and kinetic energy is sometimes conserved.
When a propeller airplane takes off, how is momentum conserved?
Momentum is conserved because molecules in the air move as the propeller pushes them.
When an inflated balloon is released with its end unsealed and takes off across the room, how is momentum conserved?
Momentum is conserved because the air molecules inside the balloon are moving out in the opposite direction from the balloon's movement.
Torque in the metric system is measured in units of?
Newton Meters (Nm)
Law of inertia
Newton's first law of motion
Is rotational kinetic energy a vector quantity?
No
If objects on the Moon weigh 1/6 the amount they weigh on Earth, what should one conclude about the mass of objects on the Moon?
Nothing. The mass of objects are the same everywhere.
Torque in the metric system is measured in units of
N·m
When the same net force is applied to object A and object B, object A has an acceleration three times that of object B. Which of the following is correct?
Object A has one-third the mass of object B.
Pat and Chris both travel from Los Angeles to New York along the same route and starting at the same time. Pat rides a bicycle while Chris drives a fancy sports car. Unfortunately, Chris's car breaks down in Phoenix for over a week, causing the two to arrive in New York at exactly the same time. Which statement is true?
Pat and Chris had the same average speed.
What results when the net force on an object increases?
Proportionally increased acceleration.
Velocity
Speed with a direction
Kinetic Energy
The energy of motion, KE = (0.5)(m)(v)^2
Magnitude
The size of a vector quantity
Formula for vertical speed after x amount of time
V0y + (a)(t) V0y = initial vertical speed a = acceleration (-9.8) t = time in seconds
Time in air formula
V=V0+a(.5t) V=Velocity (0) V0= Initial Velocity a=acceleration (-9.8) t=time
Height Formula
V^2=V0^2 + 2aΔy V=velocity at desired height (Max Height: V=0) V0^2=initial velocity squared a=acceleration (-9.8 m/s) Δy=height
Change in velocity equation
Vf-Vi
final velocity equation
Vi + ΔV= Vf
What arrangement of the masses would enable a child to begin to twirl a rod most easily, as might a cheerleader?
With the weight as close to the middle as possible (assuming there was a convenient place to hold the rod with this arrangement).
Is a state where any small rotation results in a torque that acts produce rotation back in the opposite direction a Stable equilibrium?
Yes
Circular acceleration equation
a = (V^2)/r V = Velocity r = Radius
Elastic
a collision or interaction in which kinetic energy is conserved
Acceleration formula
a= (Vf-Vi)/time
In uniform circular motion the .....
acceleration is perpendicular to the velocity.
law of universal gravitation
all masses exert forces on all other masses
Why does "banking" (or tilting) a turning road create centripetal force?
because the angle of the roadway creates a centripetal force
In the law of universal gravitation the force ____ as the mass increases and ____ as the distance increases.
increases ... decreases
The rotational inertia of an object increases as the mass ____ and the distance of the mass from the center of rotation ____.
increases ... increases
rotational kinetic energy
kinetic energy associated with the rotation of a body
What kind of momentum do objects in translational motion have?
linear
If we use plus and minus signs to indicate the directions of velocity and acceleration, in which of the following situations does the object speed up?
negative velocity and negative acceleration
When an object such as a monkey wrench is tossed into the air, what will the wrench do?
rotate around its center of mass while its center of mass undergoes translational motion
What kind of momentum do objects in rotational motion have?
rotational
An object's resistance to a change in its rotational velocity is called its
rotational inertia
When an object is spinning in place, what is it experiencing?
rotational motion
joule
the SI unit of energy and work, equal to 1 newton acting through a distance of 1 meter
meter
the SI unit of length
Kilogram
the SI unit of mass
Watt
the SI unit of power, 1 Joule per second
Centripetal acceleration
the acceleration of an object toward the center of its circular path
rotational speed
the angle of rotation or revolution divided by the time taken
center of mass
the balance point of an object. This location has the same translational motion as the object would if it were shrunk to a point
angular displacement
the change in angular position, measured in degrees, radians, or number of revolutions
rotational acceleration
the change in rotational velocity divided by the time it takes to make the change
The work that a force does by acting on an object is equal to what?
the product of force (in the direction of motion) and distance and is positive if the force and motion are in the same direction
Where is the center of mass of the Earth-Moon system?
under the surface of the Earth
If the net force on a hot-air balloon is directed straight upward, which way does the acceleration point?
upward
Imagine that you are pulling your little sister on a sled and that the sled is speeding up. The diagram shown here is the free-body diagram for the sled. The net force on the sled in the vertical (up/down) direction is _____, but the net force in the horizontal direction is _____.
zero/pointing to the right
How many significant figures are in 0.0100
3
The base SI unit for length is the ________
meter
What is another simple way to describe the weight of an object?
the magnitude of the force attracting it toward Earth's surface
What does an exponent, such as the 4 in the expression 9^4, mean?
the number of times the number before the exponent is multiplied by itself (9 ✕ 9 ✕ 9 ✕ 9)
Three horses are side by side on a merry go round: one at the edge, one near the axis, and one in between. Each horse has the same angular speed. Which horse has the greatest linear speed?
The horse at the edge
Three horses are side-by-side on a merry-go-round: one at the edge, one near the axis, and one in between. Each horse has the same angular speed. Which horse has the smallest linear speed?
The horse nearest the axis.
What is an example of an inverse-square?
The law of universal gravitation; the force is inversely proportional to the square of the distance
Which is true about representing a vector quantity?
The length of the arrow represents the magnitude of the vector and the direction of the arrow represents the direction of the vector.
In these figures, we see a boy named Billy riding a carnival ride called the Rotor and the free-body diagram for the forces acting on him. What must be the magnitudes of the vectors fwall,Billy and WEarth,Billy if Billy remains at the same height along the wall?
The magnitudes of fwall,Billy and WEarth,Billy are equal.
Newton's Second law of motion
The net force on an object is equal to its mass times its acceleration. the net force and the acceleration are vectors that always point in the same direction
centripetal force
The net force required to keep an object moving in a circular path. This force is directed toward the center of the circular path
Which of these is undergoes circular motion?
a satellite orbiting the Earth
linear momentum
a vector equal to the product of an object's mass and its velocity, p = mv
rotational velocity
a vector quantity that includes the rotational speed and direction of the axis of rotation
Ignoring air resistance, which of these is the acceleration of a falling object?
about 10 (meters per second) per second
What is the agreed-upon direction of rotational velocity?
along the axis of rotation in the direction your thumb would point if the fingers of your right hand curl along the motion of the spinning object
A gravitational field is all of the following, EXCEPT?
always the same regardless of how the objects move
A ball thrown vertically upward, at the top of its path (just before it starts to fall) has which of the following?
an instantaneous speed of zero
How small a time interval is needed for a good calculation of instantaneous speed?
an interval short enough so that the answer won't change very much if you use a shorter one
Which unit is a unit of acceleration?
meters per second per second
What two facts did Newton need to be able to calculate the acceleration of the Moon?
the distance to the Moon and the time it takes the Moon to make one revolution
average acceleration formula
((final speed)-(initial speed))/(time)
Gravitational force on a satellite formula
(G)(((Mp)(Ms))/(r^2)) G = Gravitational Constant Mp = Mass of Planet in kg Ms = Mass of Satelite in kg r = Radius in km
Gravity of planet formula
(G)(M)/r^2 G = Gravitational Constant M = Mass in kg r = Radius in km
Mass based off of net force formula
(Net Force) / (acceleration)
Acceleration due to gravity formula
(Net Force)/(mass)
Velocity after a period of time for an object thrown up formula
(initial velocity) + ((Gravity)(time))
Net force formula
(mass)*(acceleration)
Distance traveled formula
(speed)*(time)
A tennis ball (m = 0.2 kg) is thrown at a brick wall. It is traveling horizontally at 13 m/s just before hitting the wall and rebounds from the wall at 10 m/s, still traveling horizontally. The ball is in contact with the wall for 0.02 s. What is the magnitude of the average force of the wall on the ball?
-230
A very hard rubber ball (m = 0.2 kg) is falling vertically at 5 m/s just before it bounces on the floor. The ball rebounds back at essentially the same speed. If the collision with the floor lasts 0.05 s, what is the average force exerted by the floor on the ball?
-40
During a physics experiment, a fan is used to apply a push to a cart on a horizontal track. A student would like the net force on the cart to be 12 N to the right. The student knows that the friction force on the cart by the track will be 3 N to the left. The fan should exert a force of
15 N to the right
If a hair dryer is rated at 1500 W, how much energy does it require in 6 minutes?
150 Watt hours
A child with a mass of 25 kg is riding on a merry-go-round. If the child has a speed of 3 m/s and is located 2 m from the center of the merry-go-round, what is the child's angular momentum?
150 kg·m^2/s
a 30-kg block is lifted vertically 50 meters from the surface of the earth. What is the change in the gravitational potential block?
15000 J
A blue 5000-kg freight car moving at 3 m/s runs into a red 10,000 kg freight car moving at -2 m/s. They couple upon collision and move away as one body. What is the momentum of the blue freight car before the collision? What is the momentum of the red freight car before the collision? What is the total momentum before the collision? What is the velocity of the cars after the collision?
15000 kg m/s -20000 kg m/s -5000 kg m/s -0.33 m/s
At an average speed of 9 m/s, how many kilometers can a cyclist travel in a 10 hour day?
324 km
How many seconds are in an hour?
3600
a meter stick is balanced on a stand. If you place a 50 g mass on one side at a distance of 15 cm from the center, how far from the center would you place a 20 g mass on the other side so that the system balances?
37.5 cm
An atomic mass unit is measured at 1.660 x 10^27 kg and the numerical part has ______ significant digits
4
If a cheetah runs at 25 m/s, how long will it take a cheetah to run a 100 m dash?
4 seconds
A meter stick is balanced on a stand. If you place a 50-g mass on one side at a distance of 20 cm from the center, how far from the center would you place a 25-g mass on the other side so that the system balances?
40 cm
A uniform, solid flywheel of radius 1.4 m and mass 15 kg rotates at 2.7 rad/s What is the magnitude of the flywheel's angular momentum? [ Iflywheel = (1/2) * m * r^2 ]
40 kg∙m^2/s
The gravitational force between two metal spheres in outer space is 1000 N. How large would this force be if each of the two spheres had twice the mass?
4000 N
How much work does a 57 kg person do against gravity in walking up a trail that gains 750 m in elevation?
418.95 kJ
You are holding a 6-kg dumbbell straight out at arm's length. Assuming your arm is 0.70 m long, what torque is the dumbbell exerting on your shoulder?
42 N·m
A child with a mass of 35 kg is riding on a merry go round. If the child has a speed of 4 m/s and is located 3 m from the center, what is the child's angular momentum?
420
At exactly noon, you pass mile marker 206 in your car. At 2:30 p.m. you pull into a rest stop at mile marker 357. What was your average speed during this time?
60.4 mph
A box is moved 20 m across a floor by a force of 30 N acting along the direction of motion. The work done by the force is
600 J
A salesperson claims a 1310 kg car has an average acceleration of 5 m/s2 from a standing start to 100 km/h. What average net force is required to do this?
6550 N
Express 0.0074020 in proper scientific notation. (Keep track of significant figures)
7.4020 x 10^-3
A 30-06 bullet has a mass of 0.010 kg. If the average force on the bullet is 7300 N, what is the bullet's average acceleration?
730000 m/s^2
A 1800-kg car accelerates from a speed of 11 m/s to 34 m/s in 21 seconds. What is the change in kinetic energy of the car? What is the Work done by the engine? How much power is used during this process?
931500 J 931500 J 44400 W
If a 56 kg sprinter can accelerate from a standing start to a speed of 10 m/s in 3 s, what average power is generated?
933.33
A coach is hitting pop flies to the outfielders. If the baseball (mass = 145 g) stays in contact with the bat for 0.09 s and leaves the bat with a speed of 62 m/s, what is the average force acting on the ball?
99.89
In Galileo's thought experiment about rolling balls, Galileo argued which of the following?
A ball rolling on a the level surface continues at the same speed.
What is required to change an object's linear momentum?
A net force
In a rollercoaster, provided losses of thermal energy because of friction can be neglected, which of the following is true? A. The kinetic energy decreases as the car moves to the top of the slope. B. The mechanical energy increases as the car moves to the top of the slope. C. The mechanical energy decreases as the car moves to the top of the slope. D. The rollercoaster moves at constant speed as its height above the ground increases. E. The gravitational potential energy decreases as the car moves to the top of the slope.
A. The kinetic energy decreases as the car moves to the top of the slope.
What is Newton's first law?
An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
Which of the following could happen if there were no air resistance and no gravity?
An object thrown at an angle upward would keep going up in the same direction for ever and never come down.
In attempting to pull a 1500 kilogram car out of a ditch, Arnold exerts a force of 400 newtons for three seconds, Bob exerts a force of 500 newtons for 2 seconds, and Cecil exerts a force of 200 newtons for four seconds. the car does not move at all. Who provided the greatest impulse?
Arnold
A 1200 kg car traveling north at 14 m/s is rear-ended by a 2000 kg truck traveling at 20 m/s. What is the total momentum before and after the collision?
Before Collision: 56800 After Collision: 56800
How is force measured?
By the acceleration it produces on a standard isolated object (in Newtons)
inverse square
Describes a relationship in which a quantity is related to the reciprocal of the square of a second quantity
why is the kinetic energy gained by a falling ball equal to the change of potential energy? (Assuming no loss of energy due to friction.)
Energy conservation requires that the total energy remains constant. In this example, the total energy is either in the form of kinetic energy or potential energy.
What is Newton's third law?
For every action there is an equal and opposite reaction
Why does Michael Jordan appear to defy gravity as he slam dunks the ball? (After you have thought about this question, see page 68 of your textbook.)
His motion is that of a projectile, and a projectile's motion is such that its vertical speed is minimal while at the high point of its trajectory.
Newton's third law of motion
If an object exerts a force on a second object, the second object exerts an equal force back on the first object
Conservation of linear momentum
If the net external force on a system is zero, the total linear momentum of the system does not change
What is Newton's first law as applied to rotation?
In the absence an external interaction, the angular velocity of an object remains constant.
Which of these is an accurate statement of Newton's first law?
In the absence of an unbalanced force, the velocity of an object remains constant.
When a jet airplane takes off, how is momentum conserved?
Momentum is conserved because the air rushing out of the jet engine is moving out in the direction opposite to the plane's movement.
If you began at rest and ended at rest, and the average speed of your trip was 10 kmph, which is true?
Sometimes you were going faster than 10 kph.
What did Aristotle believe?
That the speed at which objects fall depends on both their weight and the medium they fall through (and he was partly right).
Which of the following statements about the Moon is correct?
The Moon experiences a centripetal acceleration toward Earth.
Newton
The SI unit of force. A net force on a second object exerts an equal force back on the first object
Describe projectile motion
The acceleration of the projectile is constant throughout the flight. The force on the projectile is constant throughout the flight. The horizontal and vertical motions are independent.
Center of Mass
The balance point of an object. This location has the same translational motion as the object would if it were shrunk to a point.
If you are whirling a ball on a string and you suddenly cut the string, what happens?
The ball goes off in a straight line based on where it was heading when the string was cut.
In this photo, a fire extinguisher provides the impulse for a hallway rocket cart. Which is NOT true about the motion of the rocket cart and person?
The cart and person are propelled as a result of gas from the fire extinguisher pushing against air in the room.
Why couldn't Newton determine the value of the gravitational constant?
The constant was too small to measure with existing instruments.
What happens to centripetal force when speed decreases, in the special case that the object continues moving in a circle of the same radius?
The force also decreases.
Static Friction
The frictional force between two surfaces at rest relative to each other. This force is equal and opposite to the net applied force is not large enough to make the object accelerate.
kinetic friction
The frictional force between two surfaces in relative motion. This force does not depend very much on the relative speed
If a race car is traveling around a circular track at a constant speed of 100 mph, we know that the car experiences ........
a centripetal force.
inelastic
a collision or interaction in which kinetic energy is not conserved
powers-of-ten notation
a method of writing numbers in which a number between 1 and 10 is multiplied by 10 raised to a power
centi
a prefix meaning "one hundredth"
kilo
a prefix meaning "one thousand"
milli
a prefix meaning "one thousandth"
angular momentum
a quantity giving the rotational momentum
field
a region of space that has a number or a vector assigned to every point
According to the Aristotelian view of motion, which of these would NOT work?
a rocket ship going to the moon
centrifugal
center fleeing
centripetal
center seeking
The average acceleration of an object is defined to be the
change in its velocity divided by the time it takes.
The motion of a ball or cylinder rolling down a ramp is one with
constant acceleration.
What kind of motion does a constant, non-zero torque produce on an object mounted on an axle?
constant rotational acceleration
You are standing on a bathroom scale in an elevator that is moving upward at constant speed, when suddenly the cable breaks. From just before to just after the cable breaks, the reading on the scale
decreases to zero
A football quarterback throws a long pass toward the end zone. Assume that you can neglect the effects of air resistance. At the instant the ball reaches its highest point, what is the direction of the acceleration on the ball?
down
if F1 is the force exerted on a cart by a horse and F1 is the force exerted on the horse by the cart, then F1 is (> < =) F2
equal to
A figure skater is spinning with her arms held straight out. The rotational speed of her fingertips is
equal to that of her elbows
Put femto, nano, mega, centi, tera, in the correct order from smallest to largest
femto, nano, centi, mega, tera
Which of the following could be considered to be an "accelerator" in an automobile?
gas pedal, brake pedal, steering wheel
A small block sits on a horizontal table. In one experiment, a student pushes with a horizontal force of 5 N, but the block does not move. In a second experiment, the student pushes with a horizontal force of 8 N, but the block still does not move. The magnitude of the friction force exerted on the block is
greater in the second experiment
A ball is thrown straight up into the air. If we do not ignore air resistance, the acceleration of the ball as it is traveling upward is
greater than 9.8 m/s2.
A fully-loaded trailer truck is less stable than a race car because the truck _____
has a higher center of mass.
What changed Newton's original work on the movement of the Moon around the Earth into the law of universal gravitation?
his conclusion that the same laws applied to all objects, no matter how small
The reason a figure skater spins slower as he extends his arms is because ___
his rotational inertia is greater.
The property of an object at rest to remain at rest is known as
inertia.
What is the correct unit for describing rotational acceleration?
rev/s^2
The base SI unit for time is the ________
second.
If there is no net force acting on an object, its motion will be one with ____ acceleration.
zero
