Physics 103 Final
A wheel has a radius of 0.5 m and rotates with an angular speed of 0.5 rad/s. If the wheel rolls without slipping, what is the center-of-mass speed?
.25 m/s
A 1-kg rock is suspended by a massless string from one end of a 1-m measuring stick. What is the mass of the measuring stick given the picture above?
1.0 kg
For a standing wave on a rope, the distance between two adjacent antinodes is
1/2 wavelength
A mass of 1.00 kg is attached to a spring with spring constant 100 N/m. Which of the following is the angular frequency of the motion the mass will undergo?
10 rad/sec
When two identical waves of the same wavelength and amplitude interfere in phase, the amplitude of the resulting wave is
2A
one radian is about
57.3 degrees
Two cars complete a 90-degree turn through a circular stretch of road. Car A completes the turn first and maintains a constant speed as it does so. Car B completes the turn after A, but the driver brakes and slows her car during the turn. Which of the following statements is correct?
Car A will experience a larger centripetal acceleration during the turn, but Car B will experience a larger tangential acceleration.
A child sits at the center of a rotating merry-go-round. She slides to the edge and then returns to the center. Which of the following is correct (assume negligible friction in the merry-go-round bearings)? The merry-go-round slows down, then speeds up to its original angular speed. The merry-go-round stops and remains stopped. The merry-go-round speeds up, then slows down to its original angular speed. The merry-go-round maintains a constant speed always.
Correct Answer The merry-go-round slows down, then speeds up to its original angular speed.
Rigid body A has two 1 kg masses placed 2 m apart. Rigid body B has two 2 kg masses placed 1 m apart. For a rotation axis that passes midway between the masses, the moment of inertia of rigid body A is larger than the moment of inertia of rigid body B. smaller than the moment of inertia of rigid body B. impossible to relate to rigid body B's moment of inertia. equal to the moment of inertia of rigid body B.
Correct Answer larger than the moment of inertia of rigid body B.
Imagine you are designing a vertical spinning wheel for a game show. Contestants will grab the wheel at its edge, apply a force tangent to the wheel, and watch it spin. You make two prototype wheels with the same mass and radius, but one is a solid disk while the other is a hoop. For a given contestant's applied force, the solid disk will have a larger angular acceleration. they will have equal angular accelerations. the hoop will have a larger angular acceleration.
Correct Answer the solid disk will have a larger angular acceleration.
A see-saw sits at a playground in rotational equilibrium with the board exactly horizontal. If a force is applied to the end of the board in the horizontal direction, there will be no change in angular momentum (the board will not rotate) because there is no torque on the board. there will be a change in angular momentum (the board will rotate) because a force was applied.
Correct Answer there will be no change in angular momentum (the board will not rotate) because there is no torque on the board.
When pulleys have significant mass, the tension in the string that passes over them changes as you move around the pulley. is independent of the moment of inertia of the pulley. is just the hanging mass minus the pulley mass times the acceleration due to gravity. is always constant along the string.
Correct Response changes as you move around the pulley.
Imagine you are designing a vertical spinning wheel for a game show. Contestants will grab the wheel at its edge, apply a force tangent to the wheel, and watch it spin. You make two prototype wheels with the same mass and radius, but one is a solid disk while the other is a hoop. For a given contestant's applied force, the hoop will have a larger angular acceleration. they will have equal angular accelerations. the solid disk will have a larger angular acceleration.
Correct Response the solid disk will have a larger angular acceleration.
A student can apply a torque of 15 N-m to every door (which acts like a thin rectangular sheet) she encounters. To enter a building, the student must open an outer door with a mass of 25 kg. Once inside, she must open an inner door of identical size, but the mass is only 10 kg. Which of the following is true? Neither door has an angular acceleration. The angular acceleration of the inner door is larger than the angular acceleration of the outer door. The angular acceleration of the inner door is smaller than the angular acceleration of the outer door. The angular acceleration of the inner door is the same as the angular acceleration of the outer door.
Correct Response The angular acceleration of the inner door is larger than the angular acceleration of the outer door.
A passenger car that has tires with radius = 0.3 m travels along a highway. The car pulls alongside a tractor-trailer that has tires with radius = 0.6 m and moves with the same velocity. If the tires roll without slipping, which of the following statements is correct? The angular speed of the car's tires is equal to the angular speed of the tractor's tires. The angular speed of the car's tires is smaller than the angular speed of the tractor's tires. The angular speed of the car's tires is larger than the angular speed of the tractor's tires.
Correct Response The angular speed of the car's tires is larger than the angular speed of the tractor's tires.
A single particle is a distance r from an axis of rotation. If the particle is moved to a distance 2r, which of the following correctly describes the change in the moment of inertia? The particle's moment of inertia about that axis of rotation decreases by a factor of 2. The particle's moment of inertia about that axis of rotation increases by a factor of 4. The particle's moment of inertia about that axis of rotation increases by a factor of 2. The particle's moment of inertia about that axis of rotation decreases by a factor of 4.
Correct Response The particle's moment of inertia about that axis of rotation increases by a factor of 4.
A thin rod rotates about one end with a constant angular acceleration of 0.1 rad/s^2. If the rod is modified to rotate about its mid-point with an angular acceleration of 0.1 rad/s^2, the net torque on the rod is smaller when it rotates about one end. the net torque on the rod is smaller when it rotates about its mid-point. the same amount of torque is required in each situation. no torque is required
Correct Response the net torque on the rod is smaller when it rotates about its mid-point.
Two bicyclists are riding together, each with the same speed. Cyclist A's bike has tires that are smaller than those on cyclist B's bike. As long as the tires are rolling without slipping, which of the following must be true?
Cyclist A is pedaling harder than B, so that her tires have larger ω.
Two bicyclists are riding together, each with the same speed. Cyclist A's bike has tires that are smaller than those on cyclist B's bike. As long as the tires are rolling without slipping, which of the following must be true? Cyclist A is pedaling harder than B, so that her tires have larger ω. Cyclist A is pedaling with the same intensity as B, so that their tires have the same ω. Cyclist A is pedaling easier than B, so that her tires have smaller ω.
Cyclist A is pedaling harder than B, so that her tires have larger ω.
Two identical masses are attached to two identical springs so that each mass oscillates simple harmonically. Mass A is pulled a distance x from equilibrium; mass B is pulled a distance 4x. Which of the following correctly links the energies of the two masses? EA = 16 EB, since B is pulled 4 times farther. EA = (1/16)EB, since B is pulled 4 times farther. EA = 4EB, since B is pulled 4 times farther. EA = (1/4)EB, since B is pulled 4 times farther. EA = EB, since the masses and springs are identical.
EA = (1/16)EB, since B is pulled 4 times farther.
You have 4 identical 10 kg masses. Two of the masses are connected by a very light bar with length 1 m, and the other two are connected by another very light bar with length 1.5 m. Call the short barbell A and the long barbell B. Which of the following statements is correct? It will be easier to start B rotating than A. It will be equally easy to start either barbell rotating. It will be easier to start A rotating than B.
It will be easier to start A rotating than B.
During a track meet around a circular track, two runners must stay in lanes with different radii. Julie's lane has a radius that is half as big as Joe's lane - Julie is closer to the center than Joe. If Julie and Joe both run with the same constant speed, then
Julie will complete one lap in half the time that it takes Joe to complete one lap.
During a track meet around a circular track, two runners must stay in lanes with different radii. Julie's lane has a radius that is half as big as Joe's lane - Julie is closer to the center than Joe. If Julie and Joe both run with the same constant speed, then what will happen to their centripetal acceleration
Julie will experience a centripetal acceleration that is twice as big as the one Joe experiences.
Two students are using the side of a building for stretching before a run. Student A pushes on the wall so that her arms are perpendicular to the wall. Student B pushes on the wall so that her arms make an angle smaller than 90-degrees with the wall. If the students arms are equal strength and their hands have the same area, which of the following is correct? Student B creates a greater shear stress on the wall. The students exert equal shear stresses on the wall. Student A creates a greater shear stress on the wall.
Student B creates a greater shear stress on the wall
A force is applied to the top face of an aluminum cube sitting on a level surface. The force acts at the center of the face, but it makes a 45-degree angle with the face. Which of the following statements correctly describes the situation? The cube experiences a shear only. All dimensions of the cube must shrink. The cube experiences both a stress and a shear. The cube experiences a stress only.
The cube experiences both a stress and a shear
In a lab, you are experimenting with two springs - spring A is stiff (has a large k), spring B is soft (has a small k). Spring A has a length that is twice that of spring B. If you hang an identical mass on each spring and give them the same initial displacement, which of the following is correct? The mass on spring A will have a longer period of oscillation than the mass on spring B, and the amplitude of A's motion will be larger than B's. The mass on spring A will have a shorter period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal. The mass on spring A will have a longer period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal. The mass on spring A will have a shorter period of oscillation than the mass on spring B, and the amplitude of A's motion will be larger than B's.
The mass on spring A will have a shorter period of oscillation than the mass on spring B, but the amplitudes of their motions will be equal.
A child sits at the center of a rotating merry-go-round. She slides to the edge and then returns to the center. Which of the following is correct (assume negligible friction in the merry-go-round bearings)? The merry-go-round speeds up, then slows down to its original angular speed. The merry-go-round stops and remains stopped. The merry-go-round maintains a constant speed always. The merry-go-round slows down, then speeds up to its original angular speed.
The merry-go-round slows down, then speeds up to its original angular speed.
Two identical masses (A and B) are attached to strings and spun in vertical circular paths. The string attached to mass A is twice as long as the string attached to mass B. Which of the following is correct?
The minimum speed necessary to maintain circular motion for mass A is about 40% larger than for mass B.
A common carnival ride involves a large cylindrical drum that rotates at high speed. Riders stand along the inner surface of the drum, and when it rotates they become "stuck" to the wall. Which of the following is correct?
The normal force from the wall provides the centripetal force.
A single particle is a distance r from an axis of rotation. If the particle is moved to a distance 2r, which of the following correctly describes the change in the moment of inertia? The particle's moment of inertia about that axis of rotation decreases by a factor of 2. The particle's moment of inertia about that axis of rotation increases by a factor of 2. The particle's moment of inertia about that axis of rotation increases by a factor of 4. The particle's moment of inertia about that axis of rotation decreases by a factor of 4
The particle's moment of inertia about that axis of rotation increases by a factor of 4.
Light waves are special kinds of transverse waves that always have the same speed (in vacuum). Given this, how does the wavelength of higher-frequency blue light compare to the wavelength of lower frequency red light?
The wavelength of red light is LONGER than the wavelength of blue light.
Tensile stresses pull things apart, compressional stresses push things together.
True
Two piano wires are hung from a ceiling in a lab. Each wire is connected to a 10-kg mass. The wires are both cylindrical and made from steel. If wire A has twice the diameter of wire B, which of the following correctly describes the relationships between the strains? Wire B has 2 times the strain of wire A. Wire B has 4 times the strain of wire A. Wire A has 2 times the strain of wire B. Wire A has 4 times the strain of wire B.
Wire B has 4 times the strain as wire A
You are driving a car around a circular track. Which of the following statements are true? Your angular momentum will increase if you increase your tangential speed. Your angular momentum will decrease if you increase your tangential speed. Your angular momentum will be unchanged if you change your tangential speed. Your angular momentum will increase if you decrease your tangential speed.
Your angular momentum will increase if you increase your tangential speed
You are driving a car around a circular track. Which of the following statements are true? Your angular momentum will be unchanged if you change your tangential speed. Your angular momentum will increase if you decrease your tangential speed. Your angular momentum will increase if you increase your tangential speed. Your angular momentum will decrease if you increase your tangential speed.
Your angular momentum will increase if you increase your tangential speed.
Wave motion in a material medium involves the propagation of a disturbance. interparticle interactions. the transfer of energy. all
all
For translational motion of a rigid body, only the center-of-mass has a velocity. the velocities of constituent particles depend on their locations in the body. all constituent particles of the body share the same velocity as the center-of-mass. the center-of-mass cannot move
all constituent particles of the body share the same velocity as the center-of-mass
Water waves with large amplitudes (like those that form tsunamis)
can move faster or slower than waves with smaller amplitudes.
When pulleys have significant mass, the tension in the string that passes over them is independent of the moment of inertia of the pulley. changes as you move around the pulley. is just the hanging mass minus the pulley mass times the acceleration due to gravity. is always constant along the string.
changes as you move around the pulley.
A string is clamped at both ends and plucked so it vibrates in a standing mode between the two extreme positions a and b shown in the figure. Let upward motion correspond to positive velocities. When the string is in position c (completely horizontal), the instantaneous velocity of points along the string
depends on its location
The maximum acceleration of an object in simple harmonic motion (Choose ALL correct completions) depends on the angular frequency. depends on the phase constant. depends on the amplitude. depends on the position of the object at t=0. depends on the length of the spring.
depends on the angular frequency depends on the amplitude
The maximum speed of an object in simple harmonic motion (Choose ALL correct completions) depends on the angular frequency. depends on the position of the object at t=0. depends on the phase constant. depends on the amplitude.
depends on the angular frequency depends on the amplitude
Hearing people talking around a corner of a building is an example of
diffraction
Two doors (thin rectangular sheets) have the same widths, heights, and thicknesses. Door A rotates about an axis through the center of the door Door B rotates about an axis at one edge If the doors have equal angular speeds, then the doors have equal angular momenta. door A has more angular momentum than door B. the doors have no angular momentum. door A has less angular momentum than door B.
door A has less angular momentum than door B
When describing the rotational motion of a rigid body, every particle in the body has to move with the center-of-mass velocity. every particle in the body has to move with the same angular speed. every particle in the body has to move away from the center of the circular motion. every particle in the body has to move with the same tangential speed.
every particle in the body has to move with the same angular speed.
A race car travels around a circular track. As it moves, it increases its speed around the track. In this case, the total acceleration experienced by the car is a vector that points directly at the center of the track.
false
An object moves with simple harmonic motion only if the object is a mass attached to a spring.
false
In a pendulum, tension is the restoring force.
false
The velocity vector of an object in uniform circular motion ALWAYS points towards the center of the circular path.
false
When you use a wrench to loosen or tighten a bolt, the entire force that you apply to the wrench causes a torque.
false
A ball is attached to a rope and swung in a vertical circle. The tension in the rope
has a larger magnitude when the ball is at the bottom of the circle than when it is at the top.
Imagine you have a choice to A) double the radius of a solid sphere, or B) double its angular speed. The rotational kinetic energy of the sphere decreases for A and increases for B. increases for A and decreases for B. increases by the same amount for A and B. increases by different amounts for A and B.
increases by the same amount for A and B.
The total mechanical energy of an object in simple harmonic motion slowly decreases as kinetic energy becomes potential energy. changes since the kinetic energy continuously varies. is constant. changes since the potential energy continuously varies.
is constant.
A ball is attached to a rope and is swung in a vertical circle. The centripetal force
is due to a combination of the tension in the rope and gravity.
A force acts on an object causing a torque (so the object will move along a circular path). The only component of the force that does work is the component that points away from the center of the circular path. is the component that is tangential to the circular path. is the component that points towards the center of the circular path.
is the component that is tangential to the circular path
A force acts on an object causing a torque (so the object will move along a circular path). The only component of the force that does work
is the component that is tangential to the circular path.
A string is clamped at both ends and plucked so it vibrates in a standing mode between the two extreme positions a and b shown in the figure. Let upward motion correspond to positive velocities. When the string is in position b, the instantaneous velocity of points along the string
is zero everywhere
A ball is attached to a rope and swung in a vertical circle. When the ball has the same height as the center of the circle (midway between the top and bottom),
it experiences its greatest tangential acceleration.
The best model of solar system formation is that a giant spherical gas cloud shrinks (its radius gets smaller), forming a central star. The cloud does not have any nearby neighbors that can exert forces on it. If the gas cloud is slowly rotating in its initial, large radius state, it must rotate faster after it shrinks. it must continue to rotate at the same rate after it shrinks. it must rotate slower after it shrinks. it must rotate in the other direction after it shrinks
it must rotate faster after it shrinks
In an experiment, you measure the time it takes an object in simple harmonic motion to return to its initial location. You have measured its frequency. its period. its angular frequency. its phase.
its period
In a simple pendulum, the magnitude of the force that causes simple harmonic motion is
mg sinθ.
The kinetic energy of an object that rolls without slipping is equal to twice the kinetic energy of its linear, center-of-mass motion. must have contributions from its translational and rotational motions. is determined only by the linear motion of its center-of-mass. is determined only by the rotational motion of the object. is equal to twice the kinetic energy of its rotational motion.
must have contributions from its translational and rotational motions.
A solid disk and a ring roll down an incline. The ring is slower than the disk if the radius of the ring equals the radius of the disk. if the mass of the ring equals the mass of the disk. never. The ring is always slower regardless of the relative values of the mass or radius. if both the masses and radii are equal.
never. The ring is always slower regardless of the relative values of the mass or radius.
Object A has twice the mass of object B. Object A is attached to a cable that hangs from the ceiling in a room. If object B is attached to an identical cable in the same room, then object A will have twice the period of oscillation of object B. object A will have (1/√2) times the period of oscillation of object B. object A will have √2 times the period of oscillation of object B. object A will have the same period of oscillation as object B. object A will have half the period of oscillation of object B.
object A will have the same period of oscillation as object B.
Object A has triple the mass of object B. Object A is attached to a cable that hangs from the ceiling in a room. If object B is attached to an identical cable in the same room, then object A will oscillate with √3 times the frequency of object B. object A will oscillate with (1/3) times the frequency of object B. object A will oscillate with (1/√3) times the frequency of object B. object A will oscillate with 3 times the frequency of object B. object A will oscillate with the same frequency as object B.
object A will oscillate with the same frequency as object B.
For a longitudinal wave, the direction between the wave velocity and particle oscillation is
parallel
The distance covered by an object that undergoes a 90-degree change in angular position is
pi/2 times the radial distance of the object.
A dog is tied to a stake in a yard so that the dog can run in a circular path. If he runs at constant speed, the tension in the leash at the dog's collar
points directly towards the stake.
You are using a wrench to loosen a rusty bolt. Which of the arrangements shown is most effective in loosening the bolt?
putting an extension on the end of the wrench in the same direction of the wrench and turning at a 90 degree angle
A grandfather clock depends on the period of a pendulum to keep correct time. Suppose a grandfather clock is calibrated correctly and then a mischevious child slides the bob of the pendulum down on the oscillating rod. Does the grandfather clock now run fast (more ticks per second compared to initial). slow (fewer ticks per second compared to initial). correctly (same number of ticks compared to initial).
slow (fewer ticks per second compared to initial).
When two waves meet and interfere, the resulting wave is determined by
superposition
Two solid disks rotate with the same angular speed. Disk A has a radius that is twice as large as Disk B. Compared to a point at the edge of Disk B, a point at the edge of Disk A
takes the same time to rotate one revolution.
A basketball (a thin spherical shell) and a solid plastic ball have the same mass and radius. If they are both spun about an axis along their diameters with the same angular speed, the basketball has more kinetic energy. the solid ball has more kinetic energy. they have the same kinetic energy. you cannot determine their relative kinetic energies.
the basketball has more kinetic energy.
A centripetal acceleration exists because
the direction of the velocity vector changes, even if its magnitude is constant.
If a torque does negative work on an object, the final angular speed of the object is smaller than the initial angular speed of the object. the final angular speed of the object is larger than the initial angular speed of the object. the object must rotate clockwise. the final angular speed of the object is the same as the initial angular speed of the object. the object must rotate counterclockwise.
the final angular speed of the object is smaller than the initial angular speed of the object.
A child sits at the center of a rotating merry-go-round. If she slides towards the edge, the kinetic energy of the system must increase. the kinetic energy of the system must decrease. the kinetic energy of the system must go to zero. the kinetic energy of the system should remain constant.
the kinetic energy of the system must decrease
A child sits at the center of a rotating merry-go-round. If she slides towards the edge,
the merry go round should slow down
A rigid body is spinning with a constant angular speed. As you observe it, this speed decreases, but the body remains unchanged. What can you infer? There must be some external force exerting a torque. Nothing, all objects naturally slow down. There must be some internal force exerting a torque.
there must be some external force exerting a torque
Angular kinematics and linear kinematics are analogous. Which of the following sets of analogies is correct?
theta plays a similar role to x (position) omega plays a similar role to v (velocity) alpha plays a similar role to a (acceleration)
As a car drives around a circular track at a constant speed, the acceleration vector points
towards the center of the circular track always.
A ball is attached to a rope and swung in a vertical circle. As the speed of the ball at the top of the circle increases, so too does the tension in the rope.
true
A ball is attached to a rope and swung in a vertical circle. The ball is not in uniform circular motion due to the acceleration due to gravity.
true
A ball is attached to a rope and swung in a vertical circle. The speed of the ball changes most rapidly when the ball is halfway between the top and the bottom.
true
A hockey puck sits on a small ice table which has a hole in its center. The puck is connected by a string to another mass. The string passes through the hole at the center of the table. If the puck is initially at rest, the other mass will cause the puck to accelerate towards the center of the table and allow the hanging mass to drop. If the puck is given an initial velocity perpendicular to the string, the hanging mass will not drop.
true
A race car travels around a circular track. As it moves, it increases its speed around the track. In this case, the centripetal acceleration experienced by the car is a vector that points directly at the center of the track.
true
If an object conserves angular momentum, it can only change is angular speed if its moment of inertia changes as well.
true
If wave A and wave B have the same period, but A's wavelength is twice that of B, then wave A has to move a twice the speed of B.
true
In uniform circular motion, the velocity of an object is NOT constant.
true
In uniform circular motion, the velocity vector always lies along a direction tangent to the circular path.
true
The acceleration of an object in simple harmonic motion always has a sign opposite from the sign of the position. For example, a mass with positive position must experience a negative acceleration.
true
The angular distance traveled by an object is equal to is arc length divided by its radial distance.
true
Two identical objects can have different moments of inertia depending on how they rotate.
true
For two travelling waves to form standing waves, the waves must have the same wavelength, amplitude, speed, all
wavelength, amplitude, speeds
Two solid disks rotate with the same angular speed. Disk A has a radius that is twice as large as Disk B. Compared to a point at the edge of Disk B, a point at the edge of Disk A
will have twice the centripetal acceleration.
Two solid disks rotate with the same angular speed. Disk A has a radius that is twice as large as Disk B. Compared to a point at the edge of Disk B, a point at the edge of Disk A
will have twice the linear speed.
If a mass attached to a spring is at its equilibrium position at t=0 s, which of the following can correctly describe its subsequent motion? x(t) = A tan(ωt) x(t) = A cos(ωt + φ) x(t) = A sin(ωt) x(t) = A cos(ωt)
x(t) = A sin(ωt)
As you enter a store, a turnstile bar must be rotated out of the way. One end of the bar is attached to a rotating hub, while the other is free. To minimize the amount of force that must be applied, you should push right at the middle of the bar. you should push as far from the free end of the bar as possible. you should push as close to the free end of the bar as possible. you can push at any location along the bar.
you should push as close to the free end of the bar as possible.
A bucket of water is swung around in a vertical circle in such a way that the tension in the rope disappears when the bucket is exactly overhead. The normal force exerted by the bucket on the water at this point is
zero
An object of mass m is hung from a spring and set into oscillation. The period of the oscillation is measured and recorded as T. The object of mass m is removed and replaced with an object of mass 2m. When this object is set into oscillation, the period of motion is
√2 T