Fundamentals of Physics I Final Exam Review Fall 2017
If you pitch a baseball with twice the kinetic energy you gave it in a previous pitch, the magnitude of its momentum is...
(square root of 2) times as much
Two horizontal curves on a bobsled run are banked ate the same angle, but one has twice the radius of the other. The safe speed (no friction needed to stay on the run) for the smaller radius curve is V. Therefore, the safe speed on the larger radius curve is...
1.4 V
A spherically symmetric planet has four times the Earth's mass and twice its radius. If a jar of peanut butter weighs 12. N on the surface of Earth, how much would it weigh on the surface of this planet?
12 N
A force produces power P by doing work W in a time T. what power will be produced by a force that does six times as much work in half as much time?
12P
a car of mass M, traveling with the velocity V, strikes a parked station wagon, whose mass is 2M. The bumpers lock together in this head-on collision. what fraction of the initial kinetic energy is lost in this collision?
2 / 3
car J moves twice as fast as car K, and car J has half the mass of car K. The kinetic energy of car J, compared to car K is...
2 to 1
car J moves twice as fast as car K, and car j has half the mass of the car K. the kinetic energy of car J, compared to car K is..
2 to 1
A car of mass M, traveling with a velocity V, strikes a parked station wagon, whose mass is 2 M. The bumpers lock together in this head-on inelastic collision. What fraction of the initial kinetic energy is lost in this collision?
2/3
A proton, of mass m and speed v, strikes an alpha-particle (which consists of 2 protons and 2 neutrons) at rest. If the collision is completely elastic, what speed will the alpha particle have after the collision? (assume the neutron's mass equals the proton's mass)
2/5 v
If both the mass and the velocity of a ball are tripled, the kinetic energy is increased by a factor of..
27
if both the mass and the velocity of a ball are tripled, the kinetic energy is increased by a factor of...
27
Two asteroids, of the same mass, have a gravitational potential energy U. If a third asteroid, of the same mass, moves toward them, to a position such that the distances between the three asteroids are the same, the gravitational potential energy of the system will have changed by..
2U
A tiger is running in a straight line. if we double both the mass and speed of the tiger, the magnitude of its momentum will increase by what factor?
4
Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?
50 mph to 60 mph
compared to yesterday, you did 3 times the work in one-third the time. To do so, your power output must have been...
9 times yesterday's power output
The following statements refer to man-made, artificial satellites in orbit around Earth. Which is an accurate statement?
A satellite in a large diameter circular orbit will always have a longer period of revolution about the Earth than will a satellite in a smaller circular orbit.
You and your friend want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy(U) of you and your friend, after you both reach the top, assuming that you and your friend have equal masses..
Both of you have the same amount of potential energy.
Two uniform solid balls, one of radius R and mass M, the other of radius 2R and mass 8R, roll down a high incline. they start together from rest at the top of the incline. Which one will reach the bottom of the incline first?
Both reach the bottom at the same time.
in figure 5-2, showing a pendulum, at what position is the potential energy maximum?
C
Three cars( cars L,M and N) are moving with the same speed and slam on their brakes. the most massive car is car L, and the least massive is car N. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, for which car is the amount of work done by friction in stopping it the greatest?
Car L
The magnitude of his momentum will be a maximum at which point (A, B, C, or D)?
D (the last point, right before hitting the ground)
If a stone is dropped with an initial gravitational potential energy of 100J but reaches the ground with a kinetic energy of only 75 J, this is a violation of the principle of conservation of energy.
False
Formula for Work (W)
Force (F) x Distance (D)
Average Power Formula
Force x Speed
A spaceship is traveling to the moon. At what point is it beyond the pull of Earth's gravity?
It is never beyond the pull of Earth's gravity
Two cars collide head-on on a level friction-free road. The collision was completely inelastic and both cars quickly came to rest during the collision. What is true about the velocity of this system's center of mass?
It was always zero
You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. if you had been
It would have skidded 4 times farther.
Which of the following has units of momentum?
J-s/m
A leaf falls from a tree. Compare its kinetic energy K to its potential energy U.
K increases, a U decreases.
King Kong falls from the top of the Empire State Building, through the air (air friction is present), to the ground below. How does his kinetic energy (K) just before striking the ground compare to his potential energy (U) at the top of the building?
K is less than U
King Kong falls from the top of the Empire State Building, through the air(air friction is present), to the ground below. How does his kinetic energy (K) just before striking the ground compare to his potential energy (U) at the top of the building?
K is less than U.
which of the following is not a unit of work?
Kg-m / s
A truck has four times the mass of a car and is moving with twice the speed of the car. if Kt and Kc refer to the kinetic energies of truck and car respectively, it is correct to say that..
Kt=16Kc
two men, Joel and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5 min longer. Compare the work they do.
Neither of them do any work.
A Ping-Pong ball moving East at a speed of 4 m/s collides with a stationary bowling ball. The Ping-Pong ball bounces back to the West, and the bowling ball moves very slowly to the East. Which object experiences the greater magnitude impulse during the collision?
Neither; both experienced the same magnitude impulse
Can work be done on a system if there is no motion?
No, since work involves a non-zero displacement.
Perfectly Inelastic Collison
One where the two colliding objects stick together after impact
Some automobiles have air bags installed on their dashboards as a safety measure. The impact of a collision causes the bag to inflate, and it then cushions a passenger's head when he is thrown forward in the car. Suppose that such a bag could lengthen the collision time between one's head and the dashboard by a factor of 10. What effect would this have on the force exerted on the head?
The force would be reduced by a factor of about 10
Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. in neither case does your car bounce back from the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greater impact force on your car?
The force would be the same in both cases.
Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. if there is no air resistance, when they hit the ground..
The heavier one will have twice the kinetic energy of the lighter one.
Suppose a solid uniform sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The angular velocity of the sphere at the bottom of the incline depends on..
The radius of the sphere
A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average collision force is correct?
The small car and the truck experience the same average force
A small car meshes with a large truck in a head-on collision. which of the following statements concerning the magnitude of the momentum change during the collision is correct?
The small car and the truck experience the same magnitude momentum change.
When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high?
The square root of 2 V
Work (W)
The transfer of energy from one entity to another, by way of the action of a force applied over a distance
if the force on an object is in the negative direction, the work it does on the object must be..
The work could be either positive or negative, depending on the direction the object moves.
You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.
The work is negative on the way up and positive on the way down.
In a collision between two unequal masses, which mass receives a greater magnitude impulse?
They receive equal impulses
A car, driven around a circle with a constant speed, must have...
a centripetal acceleration
Energy
a measure of the change imparted to or by a system through the action of forces
the following statements refer to man-made, artificial satellites in orbit around Earth. Which is an accurate statement?
a satellite in a large diameter circular orbit will always have a longer period of revolution about the Earth than will a satellite in a smaller circular orbit.
The ______ (theta) is between the force and displacement vectors
angle
Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy?
both are equal
Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?
both do zero work
suppose a bug spatters upon your windshield as you drive down the road. which sustains the greater change of momentum?
both the same (momentum is always conserved unless an external force is applied)
In ________ and __________, the vector sum of the momenta just before the event equals the vector sum of the momenta just after the event
collisions and explosions
Total mechanical energy is ____________ when the spring force is the only force that does work
conserved
Coefficient of Restitution =
e
in a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. the type of collision is...
elastic
The Kilowatt-Hour is a unit of ________
energy
Conservation of Energy
energy can neither be created nor destroyed, but only transformed from one kind to another
Linear momentum is always conserved, when there is not an _________ force
external
Jill does twice as much work as Jack does and in half the time. Jill's power output is..
four times Jack's power output
A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. the gravitational potential energy of the second stone compared to that of the first stone is..
four times as much
a horse-power is equal to 550....
ft-Ib/s
Consider an Earth satellite in an elliptical orbit. Its centripetal acceleration is..
g at the satellite
a person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms,
her moment of inertia increases and her angular speed decreases.
Other than watt, what is another way to measure power?
horsepower ------ 1 hp = 746 W
Consider two unequal masses, M and m. Which of the following statements is false?
if a uniform rod of mass m were to join the two masses, this would not alter the position
Conservation of Linear Momentum
if the net external force acting on a system of objects is zero, the vector sum of the momenta of the objects will remain constant
The center of mass and the center of gravity coincide
if the object is in a uniform gravitational field
When do the center of mass and the center of gravity coincide?
in a uniform gravitational field
The momentum of an isolated system is conserved.
in both elastic and inelastic collisions
The speed of Halley's comet, while traveling in its elliptical orbit around the sun,
increases as it nears the sun
The speed of Halley's comet, while traveling in its elliptical orbit around the sun..
increases as it nears the sun
A car hits another and the two bumpers lock together during the collision. Is this an elastic or inelastic collision?
inelastic
The total mechanical energy of a system..
is constant only if conservative forces act.
What is the unit for Kinetic Energy (KE)?
joules (J)
a leaf falls from a tree. compare its kinetic energy K to its potential energy U
k increases, and U decreases
Which of the following quantities are units of impulse?
kg*m2/s2 and kg*m/s
What are the two types of mechanical energy?
kinetic and potential
A solid sphere and a solid cylinder, both uniform and of the same mass and radius, roll without slipping at the same forward speed. it is correct to say that the total kinetic energy of the solid sphere is..
less than the total kinetic energy of the cylinder.
Tightrope walkers walk with a long flexible rod in order to...
lower their center of mass
How is energy transferred when work is done on an object?
mechanically
Formula for Gravitational Potential Energy (PEg)
mgh (measured in joules)
two cars suffer a head-on collision. What is conserved in the collision?
momentum
when a cannon fires a cannonball, the cannon will recoil backward because the...
momentum of the cannonball and cannon is conserved
A plane, flying horizontally, releases a bomb, which explodes before hitting the ground. Neglecting air resistance, the center of mass of the bomb fragments, just after the explosion...
moves along a parabolic path
For a spherical planet to act like a "point mass," so that externally F=GmM/r^2, it...
must have a spherical mass symmetry
two men, Jowl and Jerry, push against a wall. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do
neither of them do any work
The speed needed at the bottom of a loop-the-loop track so that a car can coast to the top, with sufficient speed to stay on the track, depends on the mass of the car. (neglect the effects of friction)....
never true
What is the SI unit of work?
newton-meter (Joule)
Does the centripetal force acting on an object do work on the object?
no, because the force and the displacement of the object are perpendicular
can work be done on a system if there is no motion?
no, since work involves a non-zero displacement
consider an ideal elastic spring. the spring constant is...
none of the answers
How many watts make up 1 Joule?
one
Perfectly Elastic Collison
one in which linear momentum is conserved
A satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. The acceleration of gravity at the satellite, as compared to the acceleration of gravity on the surface of Mars is..
one-sixteenth as much
a satellite encircles Mars at a distance above its surface equal to 3 times the radius of Mars. The acceleration of gravity at the satellite, as compared to the acceleration of gravity on the surface of Mars, is...
one-sixteenth as much
An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls..
only its kinetic energy is conserved.
in an elastic collision involving an isolated system, the final total momentum is..
only its mechanical energy is conserved
A sailboat of mass m is moving with a momentum p. Which of the following represents its kinetic energy?
p^2 / 2m
a sailboat of mass m is moving with a momentum p. which of the following represents its kinetic energy?
p^2 / 2m
Spring Potential Energy
potential energy stored as a result of deformation of an elastic object
If the units of your answer are kg*m2/s3, which of the following types of quantities could your answer be?
power
A person stands on the edge of a cliff. she throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. if the ground at the base of the cliff is level, which rock hits the ground with the greatest speed if there is no air resistance?
rock X
What type of quantity is energy?
scalar
Work is a ________ quantity
scalar
A golf ball traveling 3 m/s to the right collides in a head-on collision with a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elastic, the speed of the golf ball immediately after the collision is...
slightly less than 3 m/s
a golf ball traveling 3 m/s to the right collides in a head-on collision with a stationary bowling ball in a friction-free environment. If the collision is almost perfectly elastic, the speed of the golf ball immediately after the collision s....
slightly less than 3 m/s
A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. they are all uniform and roll without slipping. in what order do they reach the bottom?
sphere, disk, hoop
Two friends are standing on opposite ends of a canoe that is initially at rest with respect to a frictionless lake. the person in the front throws a very massive ball toward the back, and the person in the back catches it. After the ball is caught, the canoe is..
stationary
A rubber ball and a lump of clay have equal mass. they are thrown with equal speed against a wall. the ball bounces back with nearly the same speed with which it hit. the clay sticks to the wall. which one of these objects experiences the greater momentum change?
the ball
Two equal mass balls (one blue and the other gold) are dropped from the same height, and rebound off the floor. The blue ball rebounds to a higher position. Which ball is subjected to the greater magnitude impulse during its collision with the floor?
the blue ball
two equal mass balls (one blue and the other gold) are dropped from the same height, and rebound off the floor. the blue ball rebounds to a higher position. which ball is subjected to the greater magnitude impulse during its collision with the floor?
the blue ball
Kinetic Energy (KE)
the energy possessed by an object because it is in motion
Gravitational Potential Energy (PEg)
the energy possessed by an object because of the gravitational interaction
Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. both forces are applied perpendicular to the door. Which force has a greater magnitude?
the first force (at the midpoint)
automobile air bags reduce what during a collision?
the forces exerted upon the passenger
Two objects of different mass have equal, non-zero kinetic energies. Which object has the greater magnitude momentum?
the heavier object
A very elastic rubber ball is dropped from a certain height and hits the floor with a downward speed v. Since it is so elastic, the ball bounces back with the same speed v going upward. Which of the following statements about the bounce are correct?
the magnitude of the ball's momentum was the same just before and just after the bounce.
the work energy theorem says...
the net work done minus the initial kinetic energy is the final kinetic energy
the work theorem says
the net work done plus the initial kinetic energy is the final kinetic energy.
The Linear Momentum (p)
the product of a body's mass (m) and velocity (v)
Impulse
the product of a force (F) and the time internal (t) over which the force acts
If the Earth had four times its present mass, what would be its new period of revolution around the sun, compared to its present orbital period?
the same
if the Earth had four times its present mass, what would be its new period of revolution around the sun, compared to its present orbital period?
the same
The total energy of a circularly orbiting satellite is ....... the kinetic energy.
the same as
the total energy of a circularly orbiting satellite is ..... the kinetic energy
the same as
the total energy of a circularly orbiting satellite is ________ the kinetic energy
the same as
In an inelastic collision, the final total momentum is...
the same as the initial momentum
in an inelastic collision, the final total momentum is....
the same as the initial momentum
consider a small satellite moving in a circular orbit (radius r) about a spherical planet( mass M). The period does not depend upon..
the satellite mass
The Center of Mass
the single point that moves in the same way as a point mass would move when subjected to the same external forces that act on the object
Power (P)
the time rate of doing work / the rate at which energy is transferred
a truck weighs twice as much as a car, and is moving at twice the speed of the car. which statement is true about the truck's kinetic energy (K) compared to that of the car?`
the truck has 8 times the K of the car
Joule (J)
the work done by a force of a 1 N when it displaces an object 1 m in the direction of the force
Kepler's discovery that T2/r2=K applies
to elliptical orbits where r is the average distance.
The banking angle in a turn on the Olympic bobsled track is not constant, but increases upward from the horizontal. Coming around the turn, the bobsled team will intentionally "climb the wall," then go lower coming out of the turn. Why do they do this?
to increase the g-force on them
Total momentum before impact =
total momentum after impact
True or False: the amount of energy given up equals the work done
true
Swimmers at a water park have a choice of two frictionless water slides, as shown in the figures. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v1 of a swimmer reaching the bottom of slide 1 compare with v2, the speed of swimmer reaching the end of slide 2?
v1=v2
What is the SI unit of Power?
watt (W)
Work-Energy Theorem
when work is done on a point mass or a rigid body, and there is no change in PE, the energy imparted can only appear as KE
You throw a ball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down..
work up is -, and the work down is +
is it possible for a system to have negative potential energy?
yes, since the choice of the zero of potential energy is arbitrary
A race car, traveling at a constant speed of 50 m/s, drives around a circular track of radius 250 m. What angular acceleration does it experience?
zero
Work done by static friction is always..
zero
work done by static friction is always...
zero