Physics Final
he velocity of an object as a function of time is given by v = (12.5t - 7.2t^2)i + (4.3t^3)j. What is its acceleration as a function of time?
(12.5 - 14.4t)i + (12.9t^2)j
The rotational inertia of a solid uniform sphere about a diameter is (2/5)MR^2, where M is its mass and R is its radius. If the sphere is pivoted about an axis that is tangent to its surface, its rotational inertia is:
(7/5)MR^2
An elevator of mass 1000 kg ascends upward at a constant velocity. Approximately, how much work is done on the elevator by the gravitational force for every meter the elevator climbs?
-9800 J
A rifle of mass M is initially at rest but free to recoil. It fires a bullet of mass m and velocity v (relative to the ground). After firing, the velocity of the rifle (relative to the ground) is:
-mv/M
One revolution per minute is about:
.105 rad/s
An object attached to one end of a spring makes 20 complete vibrations in 10s. Its period is:
.5 sec
A boy holds a 40-N weight at arm's length for 10 s. His arm is 1.5 m above the ground. The work done by the force of the boy on the weight while he is holding it is:
0 J
An object of mass 1 kg is whirled in a horizontal circle of radius 0.5 m at a constant speed of 2 m/s. The work done on the object during one revolution is:
0 J
For a wheel spinning with constant angular acceleration on an axis through its center, the ratio of the speed of a point on the rim to the speed of a point halfway between the center and the rim is:
2
A 3-kg block, attached to a spring, executes simple harmonic motion according to x = 2cos(50t) where x is in meters and t is in seconds. The spring constant of the spring is:
7500 N/m
Which of the following is a correct statement of Newton's first law?
An object in motion will continue in motion at a constant velocity unless acted on by a net external force
A small satellite is in elliptical orbit around Earth as shown. If L denotes the magnitude of its angular momentum and K denotes kinetic energy: 1= farther from earth 2= closer
L2=L1 and K2>K1
Two objects interact with each other and with no other objects. Initially object A has a speed of 5 m/s and object B has a speed of 10 m/s. In the course of their motion they return to their initial positions. Then A has a speed of 4 m/s and B has a speed of 7 m/s. We can conclude:
ME was decreased by nonconservative forces
Which of the following bodies has the largest kinetic energy? M and 2V 3M and V 2M and 3V M and 4V 3M and 2V
Mass 2M and speed 3V
In raising an object to a given height by means of an inclined plane, as compared with raising the object vertically, there is a reduction in:
force required
The center of mass of a uniform disk of radius R is located:
at the center
A wheel starts from rest and spins with a constant angular acceleration. As time goes on the acceleration vector for a point on the rim:
increases in magnitude and becomes more nearly radial
A force on a particle is conservative if:
its work depends on the end points of the motion, not this the path between
An elastic collision is one in which:
kinetic energy and momentum are both conserved
The amount of work required to stop a moving object is equal to the:
kinetic energy of the object
What graph(s) represent motion at constant speed?
position vs time, linear increasing / velocity vs acceleration, straight line
A car accelerates from rest on a straight road. A short time later, the car decelerates to a stop and then returns to its original position in a similar manner, by speeding up and then slowing to a stop. What coordinate versus time graphs best describes the motion?
position-time, starts a zero, parabola opening down. Levels out, doesn't cross x-axis
The work done by gravity during the descent of a projectile is:
positive
The wound spring of a clock possesses:
potential but no kinetic
In simple harmonic motion, the magnitude of the acceleration is:
proportional to the displacement
A brick slides on a horizontal surface. Which of the following will increase the frictional force on it?
putting a second rick on top
Consider two planets in space that gravitationally attract each other. If the masses of both planets is doubled, and the distance between them is also doubled, then the force between them is
remains the same mass double= 4x distance doubled= 1/2^2= 1/4
The inertia of a body tends to cause the body to:
resist any change in its motion
A ball is held at a height H above a floor. It is then released and falls to the floor. If air resistance can be ignored, which of the five graphs below correctly gives the mechanical energy E of the Earth-ball system as a function of the altitude y of the ball?
straight horizontal line
What acceleration versus time graphs is correct for an object moving in a straight line at a constant velocity of 20 m/s?
straight line at x-axis
A bullet shot horizontally from a gun:
strikes the ground at approximately the same time as one dropped vertically from the same point at the same instant
Two bodies are falling with negligible air resistance, side by side, above a horizontal plane. If one of the bodies is given an additional horizontal acceleration during its descent, it:
strikes the plane at the same time as the other body
A force is applied to a billiard ball. In order to calculate the torque created by the force, you also need to know:
the location and orientation of the acid of rotation of the ball
If a projectile hits a stationary target, and the projectile stops while the target moves at the same speed as the incoming speed of the projectile,
the mass of the projectile is equal to the mass of the target
If a projectile hits a stationary target, and the projectile continues to travel in the same direction
the mass of the projectile is greater than the mass of the target
If a projectile hits a stationary target, and the projectile rebounds and travels back the way it came,
the mass of the projectile is mush less than the mass of the target
The magnitude of the acceleration of a planet in orbit around the Sun is proportional to:
the mass of the sun
Two objects A and B accelerate from rest with the same constant acceleration. Object A accelerates for twice as much time as object B, however. Which one of the following statements is true concerning these objects at the end of their respective periods of acceleration?
object a will travel four times as far as object b
A stone thrown from the top of a tall building follows a path that is:
parabolic
A ball is in free fall motion. Upward is taken to be the positive direction. The displacement of the ball is:
positive during ascent and negative during descent
What coordinate versus time graph represents the motion of an object whose speed is increasing?
positive exponential
Mass differs from weight in that:
weight is a force and mass is not
A projectile is fired over level ground with an initial velocity that has a vertical component of 20 m/s and a horizontal component of 30 m/s. Using g = 10 m/s2, the distance from launching to landing points is:
120 m
The x and y components of a displacement vector are -3.00 m and +4.00 m, respectively. What angle does this vector make with the positive x axis?
127 degrees
At a location where g = 9.80 m/s2 , an object is thrown vertically down with an initial speed of 1.00 m/s. After 5.00 s the object will have traveled:
128 m
Water drips from rest from a leaf that is 15 meters above the ground. Neglecting air resistance, what is the speed of each water drop when it hits the ground?
17 m/s
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. What is the speed of the projectile when it is at the highest point in its trajectory?
30 m/s
As a rocket is accelerating vertically upward at 9.8 m/s2 near the Earth's surface, it releases a projectile. Immediately after release the acceleration of the projectile is:
9.8 m/s^2 down
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. What is the acceleration of the projectile when it reaches its maximum height?
9.8 m/s^2, downward
If a particle's position is given by x=4-12t+3t^2, what is the velocity at t=1sec
-6 m/s
What magnitude impulse will give a 2.0-kg object a momentum change of magnitude +50 kg·m/s?
+ 50 N*s
The angular velocity of a rotating turntable is given in rad/s by ω(t) = 4.5 + 0.64t - 2.7t^2. What is its angular acceleration at t = 2.0 s?
-10 rad/s^2
The angular velocity of a rotating turntable is given in rad/s by ω(t) = 4.5 + 0.64t - 2.7t^2. What is its average angular acceleration between t = 1.0 s and t = 3.0 s?
-10 rad/s^2
A 1.2-kg mass is oscillating without friction on a spring whose spring constant is 3400 N/m. When the mass's displacement is 7.2 cm, what is its acceleration
-200 m/s^2
Block A, with a mass of 2.0 kg, moves along the x axis with a velocity of 5.0 m/s in the positive x direction. It suffers an elastic collision with block B, initially at rest, and the blocks leave the collision along the x axis. If B is much more massive than A, the velocity of A after the collision is
-5.0 m/s
A forward horizontal force of 12 N is used to pull a 240-N crate at constant velocity across a horizontal floor. The coefficient of friction is
0.05
A 0.25-kg block oscillates on the end of the spring with a spring constant of 200 N/m. If the system has an energy of 6.0 J, then the amplitude of the oscillation is:
0.24 m
A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface. The total mechanical energy is 0.12 J. The greatest speed of the block is:
0.69 m/s
A 0.50-kg block attached to an ideal spring with a spring constant of 80 N/m oscillates on a horizontal frictionless surface. When the spring is 4.0 cm longer than its equilibrium length, the speed of the block is 0.50 m/s. The greatest speed of the block is:
0.71 m/s
For a wheel spinning with constant angular acceleration on an axis through its center, the ratio of the angular speed of a point on the rim to the angular speed of a point halfway between the center of the rim is
1
A 4.0-N puck is traveling at 3.0 m/s. It strikes an 8.0-N puck, which is stationary. The two pucks stick together. Their common final speed is:
1.0 m/s
A 64-kg woman stands on frictionless level ice with a 0.10-kg stone at her feet. She kicks the stone with her foot so that she acquires a velocity of 0.0017 m/s in the forward direction. The velocity acquired by the stone is:
1.1 m/s backward
The approximate value of g at an altitude above Earth equal to one Earth diameter is:
1.1 m/s^2
Block A, with a mass of 4.0 kg, is moving with a speed of 2.0 m/s while block B, with a mass of 8.0 kg, is moving in the opposite direction with a speed of 3.0 m/s. The center of mass of the two-block system is moving with the velocity of
1.3 m/s in the same direction as B
For a completely inelastic two-body collision the kinetic energy retained by the objects is the same as:
1/2 Mv^2 (com) where M is the total mass and v(com) is the velocity at the center of mass
A 1-kg block is lifted vertically 1 m at constant speed by a boy. The work done by the boy is about:
10 J
An object at the surface of Earth (at a distance R from the center of Earth) weighs 90 N. Its weight at a distance 3R from the center of Earth is
10 N
A particle moves in simple harmonic motion according to x = 2cos(50t), where x is in meters and t is in seconds. Its maximum velocity is:
100 m/s
An escalator is used to move 20 people (60 kg each) per minute from the first floor of a department store to the second floor, 5 m above. The power required is approximately:
1000 W
Neglecting air resistance, a 1.0-kg projectile has an escape velocity of about 11 km/s at the surface of Earth. The corresponding escape velocity for a 2.0 kg projectile is:
11 km/s
A 0.20-kg particle moves along the x axis under the influence of a conservative force. The potential energy is given by U(x) = (8.0 J/m^2)x^2 + (2.0 J/m^2)x^4 where x is in coordinate of the particle. If the particle has a speed of 5.0 m/s when it is at x = 1.0 m, its speed when it is at the origin is:
11 m/s
Four identical particles, each with mass m, are arranged in the x, y plane as shown. They are connected by light sticks to form a rigid body. If m = 2.0 kg and a = 1.0 m, the rotational inertia of this array about the y-axis is: (just go look at photo in chapter 10)
12 kg*m^2
An object attached to one end of a spring makes 20 vibrations in 10 seconds. Its angular frequency is:
12.6 rad/sec
A 0.3 kg rubber ball is dropped from the window of a building. It strikes the sidewalk below at 30 m/s and rebounds up at 20 m/s. The magnitude of the impulse due to the collision with the sidewalk is:
15 N*s
A 5.0-kg cart is moving horizontally at 6.0 m/s. In order to change its speed to 10.0 m/s, the net work done on the cart must be:
160 J
A wheel initially has an angular velocity of 18 rad/s. It has a constant angular acceleration of 2.0 rad/s^2 and is slowing at first. What time elapses before its angular velocity is 18 rad/s in the direction opposite to its initial angular velocity?
18 sec
A projectile of mass 0.50 kg is fired with an initial speed of 10 m/s at an angle of 60° above the horizontal. The potential energy of the projectile-Earth system when the projectile is at its highest point (relative to the potential energy when the projectile is at ground level) is:
18.75 J
Two objects with masses, m1 and m2, have the same kinetic energy and are both moving to the right. The same constant force is applied to the left to both masses. If m1 = 4m2, the ratio of the stopping distance of m1 to that of m2 is:
1:1
For a wheel spinning on an axis through its center, the ratio of the radial acceleration of a point on the rim to the radial acceleration of a point halfway between the center and the rim is:
2
For a wheel spinning on an axis through its center, the ratio of the tangential acceleration of a point on the rim to the tangential acceleration of a point halfway between the center and the rim is:
2
Which of the following is not possible? 1. a body travels with a northward velocity and acceleration 2. a body travels with a constant velocity and time varying acceleration 3. a body travel with a northward velocity and southward acceleration 4. a body has zero velocity and non-zero acceleration
2
An object attached to one end of a spring makes 20 vibrations in 10 seconds. Its frequency is:
2 Hz
The meter stick shown below rotates about an axis through the point marked •, 20 cm from one end. Five forces act on the stick: one at each end (1 and 5), one at the pivot point(2), and two 40 cm from one end (3 and 4), as shown(look up chapter 10). The magnitudes of the forces are all the same. Rank the forces according to the magnitudes of the torques they produce about the pivot point, least to greatest.
2 and 5 tie, then 4, then 1 and 3 tie
This plot shows a mass oscillating as x = xm cos (ωt + φ). What are xm and φ?
2 m, 90 degrees
Three particles, two with mass m and one mass M, might be arranged in any of the four configurations known below. Rank the configurations according to the magnitude of the gravitational force on M, least to greatest. (look up chapter 13 mc)
2, 1, 3, 4
A toy cork gun contains a spring whose spring constant is 10.0 N/m. The spring is compressed 5.00 cm and then used to propel a 6.00-g cork. The cork, however, sticks to the spring for 1.00 cm beyond its unstretched length before separation occurs. The muzzle velocity of this cork is:
2.00 m/s
If a wheel is turning at 3.0 rad/s, the time it takes to complete one revolution is about:
2.1 sec
A particle moves 5 m in the positive x-direction while being acted upon by a constant force = (4 N)i + (2 N )j - (4 N)k. The work done on the particle by this force is:
20 J
A meter stick on a horizontal frictionless table top is pivoted at the 80-cm mark. A horizontal force (F1) is applied perpendicularly to the end of the stick at 0 cm, as shown. A second horizontal force F2 (not shown) is applied at the 100-cm end of the stick. If the stick does not rotate:
2>1 for all orientations of 2
The figure shows forces acting on a meter stick, which is constrained to rotate around the axis indicated by the dot •. Which force(s) create a positive torque around that axis?
3 and 4 only
A small object of mass m, on the end of a light cord, is held horizontally at a distance r from a fixed support as shown. The object is then released. What is the tension in the cord when the object is at the lowest point of its swing?
3 mg
A crate moves 10 m to the right on a horizontal surface as a woman pulls on it with a 10-N force. Rank the situations shown below according to the work done by her force, least to greatest. 1= horizontal force 2= force down 3= force up at top of the box
3,2,1
A wheel is spinning at 27 rad/s but is slowing with an angular acceleration that has a magnitude given by (3.0 rad/s^4)t^2. It stops in a time of:
3.0 sec
The string in the figure is 50 cm long. When the ball is released from rest, it swings along the dotted arc. How fast is it going at the lowest point in its swing?
3.1 m/s
Ten seconds after an electric fan is turned on, the fan rotates at 300 rev/min. Its average angular acceleration is:
3.14 rad/s^2
Mercury has a radius of about 0.38 Earth radius and a mass of only 0.055 Earth's mass. Estimate the acceleration due to gravity on the surface of Mercury. Let ag = 10 m/s2 on the surface of the Earth.
3.81 m/s^2
Two blocks (A and B) are in contact on a horizontal frictionless surface. A 36-N constant force is applied to A as shown (to the right). The magnitude of the force of A on B is:
30 N
A 6.0-kg block is released from rest 80 m above the ground. When it has fallen 60 m its kinetic energy is approximately:
3500 J also 2.0 kg at 80m and fallen 30m= 600J
Two bodies, A and B, have equal kinetic energies. The mass of A is nine times that of B. The ratio of the momentum of A to that of B is:
3:1
Two wheels are identical but wheel B is spinning with twice the angular speed of wheel A. The ratio of the magnitude of the radial acceleration of a point on the rim of B to the magnitude of the radial acceleration of a point on the rim of A is:
4
The force on a particle is given by F(t) = 0.71 t + 1.2 t^2, in N. If the force acts from t = 0 to t = 2.0 s, the total impulse is:
4.6 kg*m/s
An ideal spring is used to fire a 15.0-g block horizontally. The spring has a spring constant of 20 N/m and is initially compressed by 7.0 cm. The kinetic energy of the block as it leaves the spring is:
4.9 X 10^-2 J
A block slides down a frictionless plane that makes an angle of 30° with the horizontal. The acceleration of the block is:
4.90 m/s^2
A 2-kg block is thrown upward from a point 20 m above the Earth's surface. At what height above Earth's surface will the gravitational potential energy of the Earth-block system have increased by 500 J?
46 m
A radian is about:
57 degrees
A simple pendulum consists of a 2.0 kg mass attached to a string. It is released from rest at X as shown. Its speed at the lowest point Y is:
6.0 m/s
A 0.25-kg block oscillates on the end of the spring with a spring constant of 200 N/m. If the system has an energy of 6.0 J, then the maximum speed of the block is:
6.9 m/s
If a wheel turning at a constant rate completes 100 revolutions in 10 s its angular speed is:
63 rad/sec
The escape velocity at the surface of Earth is approximately 11 km/s. What is the mass, in units of ME (the mass of the Earth), of a planet with twice the radius of Earth for which the escape speed is twice that for Earth
8 ME
The system shown remains at rest. The force of friction on the block on the slope is: (image= incline plane with block, off the side is a pulley with block)
8 N
A man is marooned at rest on level frictionless ice. In desperation, he hurls his shoe to the right at 15 m/s. If the man weighs 720 N and the shoe weighs 4.0 N, the man moves to the left at approximately:
8.3 x 10^-2 m/s
A circular saw is powered by a motor. When the saw is used to cut wood, the wood exerts a torque of 0.80 N·m on the saw blade. If the blade rotates with a constant angular velocity of 20 rad/s the work done on the blade by the motor in 1.0 min is:
960 J
A 2.5-kg stone is released from rest and falls toward Earth. After 4.0 s, the magnitude of its momentum is:
98 kgm/s
An object of mass m, oscillating on the end of a spring with spring constant k has amplitude A. Its maximum speed is:
A* SQRT k/m
When a certain rubber band is stretched a distance x, it exerts a restoring force of magnitude F = Ax, where A is a constant. The work done by a person in stretching this rubber band from x = 0 to x = L is:
AL^2/2
Three vectors, A ,B , and C add together to yield zero: A+ B+ C= 0. The vectors A and C point in opposite directions and their magnitudes are related by the expression: A = 2C. Which one of the following conclusions is correct?
B and C have equal magnitudes and point in the same direction
Which of the five graphs correctly shows the potential energy of a spring as a function of its elongation x?
Exponential up starting at orgin
The center of mass of a system of particles obeys an equation similar to Newton's second law F=ma where:
F is the total external force and m is the total mass of the system
A woman pushes a box of weight W with a constant horizontal force of magnitude F. The floor is rough and has a frictional force of magnitude fk acting on the box. If the box moves with constant velocity, then which statement must be true about the magnitudes of the forces?
F=fk
A man pulls a sled along a rough horizontal surface by applying a constant force at an angle θ above the horizontal. In pulling the sled a horizontal distance d, the work done by the man is: What if it was an inclined plane?
Fd cos theta incline W=Fd
An elevator is rising at constant speed. Consider the following statements: I. the upward cable force is constant II. the kinetic energy of the elevator is constant III. the gravitational potential energy of the Earth-elevator system is constant IV. the acceleration of the elevator is zero V. the mechanical energy of the Earth-elevator system is constant
I, II, and IV are true
What is the relationship between instantaneous speed and instantaneous velocity?
Instantaneous speed is the magnitude of the instantaneous velocity
Object 1 of mass m moves with a speed of v in the positive x-direction. Object 2 of mass 3m moves with a speed of 4v in the negative x-direction. How does the kinetic energy of object 2 (K2) compare to the kinetic energy of object 1 (K1)?
K2= 48K1
A particle is in simple harmonic motion along the x axis. The amplitude of the motion is xm. At one point in its motion its kinetic energy is K = 5 J and its potential energy (measured with U = 0 at x = 0) is U = 3 J. When it is at x = xm, the kinetic and potential energies are:
K= 0 J and U= 8 J
Objects A and B interact with each other via both conservative and nonconservative forces. Let KA and KB be the kinetic energies, U be the potential energy, and Eint be the internal energy. If no external agent does work on the objects then:
Ka + Kb + U + Eint is conserved
Let U be the potential energy (with the zero at zero displacement) and K be the kinetic energy of a simple harmonic oscillator. Uavg and Kavg are the average values over a cycle. Then:
Kavg=Uavg
A boy pulls a wooden box along a rough horizontal floor at a constant speed with force P. f is the magnitude of the force of friction, N is the magnitude of the normal force, and Fg is the magnitude of the force of gravity. Which of the following must be true?
P=f and N=Fs
A boy pulls a wooden box along a rough horizontal floor at constant speed by a diagonal force P (pulling up). f is the magnitude of the force of friction, N is the magnitude of the normal force, and Fg is the magnitude of the force of gravity. Which of the following must be true?
P>f and N<Fs
A planet travels in an elliptical orbit about a star as shown. At what pair of points is the speed of the planet the same?
Q and U (top and bottom of orbit, parallel with each other)
A weight suspended from an ideal spring oscillates up and down with a period T. If the amplitude of the oscillation is doubled, the period will be:
T
A block of mass m is pulled at constant velocity along a rough horizontal floor by an applied force diagonal, pulled up. The magnitude of frictional force is:
T cos theta
A simple harmonic oscillator consists of a mass m and an ideal spring with spring constant k. The particle oscillates as shown in (i) with period T. If the spring is cut in half and used with the same particle, as shown in (ii), the period will be:
T/SQRT2
Why do raindrops fall with constant speed during the later stages of their descent?
The air resistance just balances the force of gravity
A racecar, traveling at constant speed, makes one lap around a circular track of radius r in a time t. Note: The circumference of a circle is given by C = 2 pi r. 1. What concerning this car is true?
The average speed of the car is the same over any time interval
An object rotates from θ1 to θ2 through an angle that is less than 2π radians. Which of the following represents its angular displacement?
Theta2-theta1
Uniform circular motion is the direct consequence of
a force of constant magnitude that is always directed toward the same fixed point
Which of the following is NOT required for a simple pendulum undergoing simple harmonic oscillation? a point mass a massless string a small amplitude gravitational force a large spring constant
a large spring constant
If the total momentum of a system is changing:
a net external force must be acting on the system
A good example of kinetic energy is provided by:
a tornado
The momentum of an object at a given instant is independent of its:
acceleration
In a one-dimensional collision,
all motion, both before and after the collision, must be along the same line
Two objects, one having three times the mass of the other, are dropped from the same height in a vacuum. At the end of their fall, their velocities are equal because NONE OF THESE
anything falling in the vacuum has constant velocity. all objects reach the same terminal velocity. the acceleration of the larger object is three times greater than that of the smaller object. the force of gravity is the same for both objects.
A disk is free to rotate on a fixed axis. A force of given magnitude F, in the plane of the disk, is to be applied. Of the following alternatives the greatest angular acceleration is obtained if the force is:
applied tangentially to the rim
A force with a given magnitude is to be applied to a wheel. The torque can be maximized by
applying the force at the rim, tangent to the rim
A lead block is suspended from your hand by a string. The reaction to the force of gravity on the block is the force exerted by the:
block on the earth
Two cars travel along a level highway. It is observed that the distance between the cars is increasing. What statment true?
both cars could be accelerating at the same rate
The center of mass of the system consisting of Earth, the Sun, and the planet Mars is:
closer to the sun that to either of the other bodies
The coordinate-time graph of an object is a straight line with a positive slope. The object has:
constant velocity
An astronaut finishes some work on the outside of his satellite, which is in circular orbit around the Earth. He leaves his wrench outside the satellite. If there is no air resistance, the wrench will:
continue in orbit with the satellite
If the angular velocity vector of a spinning body points out of the page then, when viewed from above the page, the body is spinning:
counterclockwise about an axis that is perpendicular to the page
The speed of a comet in an elliptical orbit about the sun:
decreases while it is receding from the sun
In simple harmonic motion, the restoring force must be proportional to the:
displacement
Only if a force on a particle is conservative:
does it do no work when the particle moves exactly once around any closed path
The amplitude of any oscillator will be doubled by:
doubling both the initial displacement and initial speed
A kilowatt hour is a unit of:
energy
Force:
equals the time rate of change of momentum
A crate is initially at rest on a horizontal frictionless table. A constant horizontal force F is applied. What graph is a correct plot of work W as a function of crate speed v?
exponentially up
Frequency f and angular frequency ω are related by
f=w/2pi
Consider the statement: "Earth moves in a stable orbit around the Sun and is therefore in equilibrium". The statement is:
false, because the earth has a considerable acceleration
τ = Iα for an object rotating about a fixed axis, where τ is the net torque acting on it, I is its rotational inertia, and α is its angular acceleration. This expression:
follows directly from Newton's second law
In the figure below (incline plane, mass at top), the block of mass m is at rest on an inclined plane that makes an angle θ with the horizontal. The force of static friction fs must be such that:
fs=mgsintheta
A box is pulled up a rough inclined plane with a constant velocity. Which one of the following statements concerning this situation is false? fk does negative work W of FN= 0J Net work by all forces=0 tension does positive work gravity does positive work
gravity does positive work
A planet travels in an elliptical orbit about a star X as shown. The magnitude of the acceleration of the planet is:
greatest at point W (closest to the sun)
An object moving in a circle at constant speed
has an acceleration of constant magnitude
An 8-N block slides down an incline. It has an initial speed of 7 m/s. The work done by the resultant force on this block is:
impossible to calculate without more information
A particle oscillating in simple harmonic motion is
in equilibrium at the center of its path because the acceleration is zero there
If the length of a simple pendulum is doubled, its period will
increase by a factor of sqrt2
A certain spring elongates 9 mm when it is suspended vertically and a block of mass M is hung on it. The angular frequency of this mass-spring system:
is 33 rad/s
The direction of the impulse on a struck baseball
is in the direction of the ball's change in velocity
The mass of a body:
is independent of the acceleration due to gravity
Two objects, P and Q, have the same momentum. Q can have more kinetic energy than P if it:
is moving faster than P
One-dimensional linear position is measured along a line, from a point designated x = 0. One-dimensional angular position:
is the angle that an internal reference line makes with a foxed external reference line
A projectile in flight explodes into several fragments. The total momentum of the fragments immediately after this explosion:
is the same momentum of the projectile immediately before the explosion
Two projectiles are in flight at the same time. The acceleration of one relative to the other:
is zero
A particle moves back and forth along the x axis from x = -xm to x = +xm, in simple harmonic motion with period T. At time t = 0 it is at x = +xm. When t = 0.75T:
it is at x=0 and is traveling toward x=+xm
A body at rest in a system is capable of doing work if
it is free to move in such a way as to decrease the potential energy of the system
If a satellite moves above the Earth's atmosphere in a circular orbit with constant speed, then
its acceleration is toward the earth
The center of mass of a system of particles remains at the same place if:
its is initially at rest and the external forces sum to zero
An object is raised from the surface of Earth to a height of two Earth radii above Earth. Then:
its mass remains constant and its weight decreases
A heavy wooden block is dragged by a force along a rough steel plate. The magnitude of the applied force is the same for both cases. The normal force in (1), as compared with the normal force in (2) is: (1)- flat surface Force to right (2)- incline Force pulled up
less
A uniform solid cylinder made of lead has the same mass and the same length as a uniform solid cylinder made of wood. The rotational inertia of the lead cylinder compared to the wooden one is:
less
The same heavy wooden block is dragged by a force along a rough steel plate, for two possible situations (a= flat surface, B= incline up). The magnitude of the acceleration is the same for the two situations; do not assume that the magnitude is the same. The magnitude of the frictional force in (B), as compared with that in (A) is:
less
The first graph shows the potential energy U(x) for a particle moving on the x axis. Which of the following five graphs correctly gives the force F exerted on the particle?
linear decreasing, starts positive y, crosses x-axis
What coordinate versus time graph represents the motion of an object moving with a constant nonzero speed?
linear, down to zero (/ but flipped)
Two blocks with masses m and M (stuck together) are pushed along a horizontal frictionless surface by a horizontal applied force as shown. The magnitude of the force of either of these blocks on the other is
mF/(m+M)
A block of mass m is pulled along a rough horizontal floor by an applied force diagonal, pulled up. The vertical component of the force exerted on the block by the floor is:
mg - T sintheta
For a block of mass m to slide without friction up the rise of height h shown, it must have a minimum initial kinetic energy of:
mgh
The physical quantity "impulse" has the same dimensions as that of:
momentum
An inelastic collision is one in which:
momentum is conserved but kinetic energy is not conserved
You stand on a spring scale on the floor of an elevator. Of the following, the scale shows the highest reading when the elevator:
moves upward with increasing speed or moves downward with decreasing speed
A Boston Red Sox baseball player catches a ball of mass m that is moving toward him with speed v. While bringing the ball to rest, his hand moves back a distance d. Assuming constant deceleration, the horizontal force exerted on the ball by his hand is:
mv^2/2d
The center of mass of Earth's atmosphere is:
near the center of the earth
Throughout a time interval, while the speed of a particle increases as it moves along the x axis, its velocity and acceleration could be:
negative and negative
An artificial satellite of the Earth releases a bomb. Neglecting air resistance, the bomb will:
never strike earth
A nonconservative force
none of the above
A simple pendulum has length L and period T. As it passes through its equilibrium position, the string is suddenly clamped at its mid-point. The period then becomes: 2T T T/2 T/4 none
none of the above
Acceleration is always in the direction:
of the net force
A block slides across a rough horizontal table top. The work done by friction changes:
only the kinetic and thermal energies
A ball hits a wall and rebounds with the same speed, as diagrammed below (V shape). The changes in the components of the momentum of the ball are
sum px=0, sum py>0
In uniform circular motion,
the acceleration and the velocity are always perpendicular. both the acceleration and the velocity are continually changing direction.
A football is kicked at an angle theta with respect to the horizontal. Which one of the following statements best describes the acceleration of the football during this event if air resistance is neglected?
the acceleration is 9.8 m/s^2 at all times
In simple harmonic motion
the acceleration is greatest at the maximum displacement
An oscillatory motion must be simple harmonic if:
the acceleration varies sinusoidally with time
For a block resting on a table, the 3rd law force pair for the weight of the block is:
the block pulling up on the earth
The angular velocity vector of a spinning body points out of the page. If the angular acceleration vector points into the page then:
the body is slowing down
An object moves in a circle at constant speed. The work done by the centripetal force is zero because:
the centripetal force is perpendicular to the velocity
In simple harmonic motion, the magnitude of the acceleration is greatest when:
the displacement is maximum
The center of mass of a system of particles has a constant velocity if:
the external forces acting on a particles of the system sum to zero
A book rests on a table, exerting a downward force on the table. The reaction to this force is:
the force of the table of the book
The law of conservation of momentum applies to a system of colliding objects only if:
the net external impulse is zero
Two uniform circular disks having the same mass and the same thickness are made from different materials. The disk with the smaller rotational inertia is:
the one made from the more dense material
In general, any surface exerts two forces on objects that are in contact with it. One force is parallel to the surface and the other is perpendicular to the surface. What are these forces called?
the parallel force is friction and the perpendicular force is the normal force
Which of the following is the difference between a simple pendulum and a physical pendulum?
the physical pendulum has an extended mass
Two particles interact by conservative forces. In addition, an external force acts on each particle. They complete round trips, ending at the points where they started. Which of the following must have the same values at the beginning and end of this trip?
the potential energy of the two-particle system
A woman lifts a barbell 2.0 m in 5.0 s. If she lifts it the same distance in 10 s, the work done by her is:
the same
A feather and a lead ball are dropped from rest in vacuum on the Moon. The acceleration of the feather is:
the same as that of the lead ball
Two bodies of unequal mass, placed at rest on a frictionless surface, are acted on by equal horizontal forces for equal times. Just after these forces are removed, the body of greater mass will have:
the same momentum as the other body
A box is on a scale. In which of these situations will the scale reading NOT equal the weight of the box?
the scale and the box are on a steep slope, held in place by friction
A block is first placed on its long side and then on its short side on the same inclined plane. The block slides down the plane on its short side but remains at rest on its long side. A possible explanation is:
the short side is smoother
A freely falling body has a constant acceleration of 9.8 m/s2 . This means that:
the speed of the body increases by 9.8 m/s during each second
At one particular moment, a subway train is moving with a negative velocity and positive acceleration. Which of the following phrases best describes the motion of this train? Assume the front of the train is pointing in the positive x direction.
the train is moving in reverse as it slows down
If a wheel turns with constant angular speed then:
the wheel turns through equal angles in equal times
A baseball is hit upward and travels along a parabolic arc before it strikes the ground. Which one of the following statements is necessarily true?
the x-component of the velocity of the ball is the same throughout the ball's flight
A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. While in flight, how do the x and y components of the velocity vector of the ball compare at the points B and C?
the x-components are the same, the y component has a larger magnitude at C than B
Equal forces act on isolated bodies A and B. The mass of B is three times that of A. The magnitude of the acceleration of A is:
three times that of B
The diagram shows a velocity-time graph for a car moving in a straight line. At point Q the car must be (graph- starts at zero, parabola opening down, p= above x-axis, q= below x-axis)
traveling in the reverse direction to that at point P
The velocity of a particle moving along the x axis changes from vi to vf. For which values of vi and vf is the total work done on the particle positive?
v1= -2 m/s, vf= -5 m/s
The linear momentum of an object at a given instant is in the same direction as its:
velocity
A golf ball is struck by a golf club and falls on a green eight feet above the tee. The potential energy of the Earth-ball system is greatest:
when the ball reaches the highest point in its flight
A block is attached to the end of an ideal spring and moved from coordinate xi to coordinate xf. The relaxed position is at x = 0. The work done by spring is positive if:
xi=-4 cm and xf=-2 cm
A drag racing car starts from rest at t = 0 and moves along a straight line with velocity given by v = bt2 , where b is a constant. The expression for the distance traveled by this car from its position at t = 0 is:
(bt^3)/3
An object has a velocity of (5.4 m/s)i - (4.8 m/s)j. Over a period of 1.3 s, its velocity changes to (1.7 m/s)i + (5.9 m/s)j. What is its acceleration?
-(2.8 m/s)i + (8.2 m/s)j
This graph (pvst) shows the position of a particle as a function of time. What is its instantaneous velocity at t = 7s (1-2 increase 0-12, 2-5 flat, 5-9 decrease to 0)
-3 m/s
This graph (pvst) shows the position of a particle as a function of time. What is its average velocity between t = 5s and t = 9s? (1-2, increases to 12, 2-5, flat, 5-9, decreases to zero)
-3 m/s
A car starts from Hither, goes 50 km in a straight line to Yon, immediately turns around, and returns to Hither. The time for this round trip is 2 hours. The magnitude of the average velocity of the car for this round trip is:
0 km/hr
A ball is thrown vertically upward from the surface of the earth. Consider the following quantities: (1) the speed of the ball; (2) the velocity of the ball; (3) the acceleration of the ball. Which of these is (are) zero when the ball has reached the maximum height?
1 and 2 only
The coordinate of an object is given as a function of time by x = 7t - 3t2 , where x is in meters and t is in seconds. Its average velocity over the interval from t = 0 to t = 2 s is:
1 m/s
The coordinate of a particle in meters is given by x(t) = 16t - 3.0t3 , where the time t is in seconds. The particle is momentarily at rest at t =
1.3 sec
What is the angle between the vectors A and - A when they are drawn from a common origin?
180 degrees
A constant force of 8.0 N is exerted for 4.0 s on a 16-kg object initially at rest. The change in speed of this object will be:
2 m/s
A 6-kg object is moving south. A net force of 12 N north on it result in the object having an acceleration of:
2 m/s^2 north
An elevator is moving upward with a speed of 11 m/s. Three seconds later, the elevator is still moving upward, but its speed has been reduced to 5.0 m/s. What is the average acceleration of the elevator during the 3.0 s interval?
2.0 m/s^2, downward
A car, initially at rest, travels 20 m in 4 s along a straight line with constant acceleration. The acceleration of the car is:
2.5 m/s^2
A stone is released from a balloon that is descending at a constant speed of 10 m/s. Neglecting air resistance, after 20 s the speed of the stone is:
206 m/s
Town A lies 20 km north of town B. Town C lies 13 km west of town A. A small plane flies directly from town B to town C. What is the displacement of the plane?
24 km, 57 degrees north of west
A physics student standing on the edge of a cliff throws a stone vertically downward with an initial speed of 10.0 m/s. The instant before the stone hits the ground below, it is traveling at a speed of 30.0 m/s. If the physics student were to throw the rock horizontally outward from the cliff instead, with the same initial speed of 10.0 m/s, what is the magnitude of the velocity of the stone just before it hits the ground?
30.0 m/s
A heavy ball falls freely, starting from rest. Between the third and fourth second of its fall it travels a distance of:
34.3 m
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. Approximately how long does it take the projectile to reach the highest point in its trajectory?
4 seconds
A projectile is shot vertically upward with a given initial velocity. It reaches a maximum height of 100 m. If on a second shot the initial velocity is doubled, then the projectile will reach a maximum height of
400 m
A plane traveling north at 200 m/s turns and then travels south at 200 m/s. The change in its velocity is:
400 m/s south
An airplane is in level flight at an altitude of 0.50 km and a speed of 150 km/h. At what distance d should it release a heavy bomb to hit the target X? Take g = 10 m/s2
417 m
An object is thrown straight up from ground level with a speed of 50 m/s. If g = 10 m/s2 its distance above ground level 1.0 second later is:
45 m
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. Determine the initial speed of the projectile.
50 m/s
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. What is the magnitude of the projectile's velocity just before it strikes the ground?
50 m/s
A projectile fired from a gun has initial horizontal and vertical components of velocity equal to 30 m/s and 40 m/s, respectively. At what angle is the projectile fired (measured with respect to the horizontal)?
53 degrees
Use the component method of vector addition to find the resultant of the following three vectors:
68 km, 86 degrees south of east
A car starts from rest and accelerates at a constant rate in a straight line. In the first second the car moves a distance of 2.0 meters. How fast will the car be moving at the end of the second second?
8.0 m/s
Two vectors A and B are added together to form a vector C. The relationship between the magnitudes of the vectors is given by: A^2 + B^2 = C^2 . Which statement concerning these vectors is true?
A and B must be right angles to each other
Two vectors A and B are added together to form a vector C. The relationship between the magnitudes of the vectors is given by A + B = C. Which one of the following statements concerning these vectors is true?
A and B must point in the same direction
A particle moves on the x-axis. When its acceleration is positive and increasing: What's not true (4 options)
Velocity must be +, Velocity must be -, it must be slowing down, it must be speeding up
Of the following situations, which one is impossible?
a body having constant velocity and variable acceleration
Which one of the following situations is not possible?
a body travels with a constant velocity and a time-varying acceleration
Which one of the following statements must be true if the expression x=Vot + 1/2at^2 is to be used?
a is constant
The diagram shows a velocity-time graph for a car moving in a straight line. At point P the car must be: (graph- starts at zero, exponential increasing)
accelerating
If you drop a rock and a feather, the rock hits the ground first. This demonstrates that:
air resistance has a larger affect on feathers than on rocks
An object rests on a horizontal frictionless surface. A net horizontal force of magnitude F is applied. This force produces an acceleration:
always
The area under a velocity-time graph represents:
displacement
An object, tied to a string, moves in a circle at constant speed on a horizontal surface as shown. The direction of the displacement of this object, as it travels from W (top of circle) to X (left of circle) is:
down to the left
A ball is thrown upwards. Its acceleration is:
downward during both the ascent and descent
Two objects are traveling around different circular orbits with constant speed. They both have the same acceleration but object A is traveling twice as fast as object B. The orbit radius for object A is _______ the orbit radius for object B.
four times
A baseball is thrown vertically into the air. The acceleration of the ball at its highest point is:
g, down
An object is thrown vertically upward with a certain initial velocity in a world where the acceleration due to gravity is 19.6 m/s2 . The height to which it rises is ____ that to which the object would rise if thrown upward with the same initial velocity on the Earth. Neglect air resistance
half
The mass and weight of a body:
have the same ratio as that of any other body and placed at that location
Which of the following is NOT an example of accelerated motion?
horizontal component of projectile motion
A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. At which point is the velocity vector changing most rapidly with time?
it is changing at the same rate at all four points
All falling objects experience some air resistance, the effect of which is to decrease acceleration. When the falling object's acceleration reaches zero, the acceleration stops changing. Therefore, if you drop an object and it falls far enough for this to happen,
its speed reaches a maximum value and then doesn't change
An object is shot vertically upward. While it is rising:
its velocity is upward and its acceleration is downward
Which of the following is NOT true of an object in free fall in the absence of air resistance?
its velocity will always be zero at some point along its path
Which of the following is true, according to Newton's second law?
the acceleration of an object is proportional to the net force on it and inversely proportional to the mass
Displacement can be obtained from:
the area under a velocity-time graph
Which one of the following statements is correct for an object in free fall released from rest?
the average velocity during the first second of time is 4.9 m/s
A ball is thrown vertically upward from the surface of the earth. The ball rises to some maximum height and falls back toward the surface of the earth. Which one of the following statements concerning this situation is true if air resistance is neglected?
the ball is a freely falling body for the duration of its flight Examples of not true as the ball rises its acceleration vector points upward the acceleration is zero at max height speed is negative as it falls back to earth the velocity and acceleration always point in the same direction
A bomber flying in level flight with constant velocity drops a bomb before it is over the target. Neglecting air resistance, which two statements are NOT true?
the horizontal velocity of the plane equals the vertical velocity of the bomb when it hits the target also not true the time of flight of the bomb is independent of the height from which it was dropped
A tennis ball is thrown upward at an angle from point A. It follows a parabolic trajectory and hits the ground at point D. At the instant shown, the ball is at point B. Point C represents the highest position of the ball above the ground. While in flight, how do the x and y components of the velocity vector of the ball compare at the points A and D?
the velocity components have the same magnitude at both points, but the directions of the y components are reversed
An object is dropped from rest. What graph correctly represents its motion? The positive direction is taken to be upward. Take careful note of the axes.
velocity-time linear downward, negative
A stone is dropped from a cliff. The graph (carefully note the axes) that best represents its motion while it falls is:
velocity-time, linear downward, negative
An object is thrown vertically into the air. What graph represents the velocity (v) of the object as a function of the time (t)? The positive direction is taken to be upward.
velocity-time, linear downward, starts above zero crosses x-axis
A puck slides across a smooth, level tabletop at height H at a constant speed vo. It slides off the edge of the table and hits the floor a distance x. What is the relationship between the distances x and H?
x=Vo SQRT(2H/g)
Is it possible for an object to have zero velocity and constant nonzero acceleration?
yes, but its velocity must be only zero for an instant
Can an object have positive acceleration and decreasing speed?
yes, possible if the initial velocity if negative
You leave your house and drive to your friend's house, where you stay a while. Then you come back home. Which of the following must be true of your trip?
your average velocity was zero
A car travels east at constant velocity. The net force on the car is:
zero
A heavy steel ball B is suspended by a cord from a block of wood W. The entire system is dropped through the air. Neglecting air resistance, the tension in the cord is:
zero
A racecar, traveling at constant speed, makes one lap around a circular track of radius r in a time t. Note: The circumference of a circle is given by C = 2 pi r Determine the magnitude of the average velocity of the car for one complete lap
zero m/s