Physics Final Concepts

In which one of the following situations will there be an increase in kinetic energy?

A fan is switched from "low speed" to "high speed."

In which one of the following systems is there a decrease in gravitational potential energy?

A girl jumps down from a bed and lands on her feet

Sometimes, even with a wrench, you cannot loosen a nut that is frozen tightly to a bolt. It is often possible to loosen the nut by slipping one end of a long pipe over the wrench handle and pushing it at the other end of the pipe. With the aid of the pipe, the applied force produces a

A greater torque

Which one of the following statements is true according to Newton's first law of motion?

A net force is required to change an object's velocity

A sound wave is generated in a tube that has one closed end. Which one of the following statements is FALSE?

A node occurs at the open end.

Which one of the following statements concerning waves is FALSE?

A wave carries particles of its medium from one place to another

An object is in simple harmonic motion. The rate at which the object oscillates may be described using the period T, the frequency f, and the angular frequency . If the angular frequency decreases, what is the effect on the period and the frequency?

The period would increase, but the frequency would decrease

On a warm spring day, you are waiting at a red traffic light listening to your favorite radio station with the windows down. The driver in a car passing you in the left turn lane at a constant speed happens to be listening to the same radio station. What do you notice as the car approaches and passes you?

The sound from the passing car seems to be at a higher frequency when approaching and at a lower frequency when moving away compared to the sound from your radio.

A piano is tuned by tightening or loosing the piano wires. When the wires are tightened, how is speed of the waves on the wire affected, if at all?

The speed is increased

Which one of the following statements concerning static and kinetic frictional forces is correct?

The static frictional force acts on an object when it is stationary and the kinetic frictional force acts on it when it is sliding

A rock is suspended from a string and moves downward at constant speed. Which one of the following statements is true concerning the tension in the string if air resistance is ignored?

The tension is equal to the weight of the rock

Which one of the following statements concerning the two "gravitational constants" G, the universal gravitational constant, and g the magnitude of the acceleration due to gravity is true?

The value of G is the same everywhere in the universe, but the value of g is not

A water skier is pulled by a boat traveling with a constant velocity. Which one of the following statements is FALSE concerning this situation?

There is a net horizontal force on the skier in the direction of the boat's velocity.

A string has one end attached to a wall and the other end attached to a motor that moves the end up and down in simple harmonic motion. The frequency of the motor is varied until a transverse standing wave is produced on the string that has four nodes. Which of the following statements concerning this situation is FALSE?

This standing wave represents the 4th harmonic.

Which one of the following descriptions indicates that the object is in translational equilibrium?

Translational equilibrium occurs if the object is at rest or moving with constant velocity.

. Under what condition(s) will an object be in equilibrium?

if it is either at rest or moving with constant velocity

A block is pulled at constant speed along a rough level surface by a rope that makes an angle with respect to the horizontal. The applied force along the rope is P. The force of kinetic friction between the block and the surface is f. Which one of the following actions will increase the frictional force on the block?

increasing the weight of the block

Which one of the following terms is used to indicate the natural tendency of an object to remain at rest or in motion at a constant speed along a straight line?

inertia

Complete the following statement: Near the surface of the earth, the weight of an object

is the gravitational force of the earth on the object

A ball is thrown vertically upward in the air. Which one of the following quantities is equal to zero at the highest point of the ball's trajectory?

kinetic energy

Complete the following statement: The phenomenon of beats occurs when an observer

listens to two tones with slightly different frequencies

Which one of the following factors is important in determining the speed of waves on a string?

mass per unit length

A standing wave is produced in a vertical tube with both ends open. Complete the following sentence: Inside the tube, air molecules are

moving up and down about their undisturbed positions

A sailboat is moving at a constant velocity. Is work being done by a net external force acting on the boat?

no

Is it correct to conclude that one engine is doing twice the work that another is doing just because it is generating twice the power

no

What is the distance between two successive antinodes of a standing wave?

one-half wavelength

An object in simple harmonic motion is observed to move between a maximum position and a minimum position. The minimum time that elapses between the object being at its maximum position and when it returns to that maximum position is equal to which of the following parameters?

period

is there less force required to push or pull a sled

pull

What is the meaning of the word "normal" in the term "normal force?"

that it is directed perpendicular to a surface

Complete the following sentence: In harmonic motion, resonance occurs when

the driving frequency is the same as the natural frequency of the system

The power due to a force depends on which of the following parameters?

the magnitude of the force and the velocity of the object

two identical blocks are being pulled on a rough surface. which statement is false

the magnitude of the force of the kinetic friction is greater for the block on the right

Complete the following statement: The term net force most accurately describes

the quantity that changes the velocity of an object.

Which one of the following superpositions will result in beats?

the superposition of waves that are identical except for slightly different frequencies

Complete the following statement: If negative work is done on a moving object,

the velocity of the object will decrease

Complete the following statement: If positive work is done on a moving object

the velocity of the object will increase

Complete the following statement: A force that acts on an object is said to be conservative if

the work it does on the object is independent of the path of the motion

Complete the following sentence: Destructive interference occurs when

two or more waves are present at the same place and the resultant disturbance has zero amplitude

The shock absorbers on a car are designed to produce what type of damping?

underdamped

A 5.0-kg ball on the end of a chain is whirled at a constant speed of 1.0 m/s in a horizontal circle of radius 3.0 m. What is the work done by the centripetal force during one revolution?

zero J

The sound intensity level is reported in decibels. If the sound intensity is at the threshold for hearing, what is the sound intensity level in decibels?

zero dB

You are riding a bicycle along the side of a road when an ambulance comes up behind you with its siren on. As the ambulance passes, you notice that the sound of the siren changes. How does it change AFTER it passes you?

The frequency continually decreases

Which one of the following statements concerning kinetic energy is true?

The kinetic energy of an object always has a positive value

An arrow is launched straight up from the surface of the Earth. Which one of the following statements describes the energy transformation of the arrow as it rises? Neglect air resistance.

The kinetic energy of the arrow decreases as the potential energy increases.

An object, which is considered a rigid body, is in equilibrium. Which one of the following statements is FALSE when determining the forces and torques acting on the object?

The linear acceleration or the angular acceleration of the object may not be equal to zero.

Which one of the following statements best explains why the weight of an object of mass m is different on Mars than it is on the Earth? Mars is smaller than Earth and also weighs less

The mass and radius of Mars are both less than those of Earth

A block is hung vertically at the end of a spring. When the block is displaced and released, it moves in simple harmonic motion. Which one of the following statements is true concerning the block?

The maximum acceleration of the block occurs when its velocity is zero

Two solid spheres have the same mass, but one is made from lead and the other from wood. How do the moments of inertia of the two spheres compare? Moment of inertia of a solid sphere is given by I = 2/5×MR2

The moment of inertia of the wood sphere is greater than that of the one made of lead.

A brick is resting on the surface of a flat board. As one end of the board is slowly raised, what change, if any, is there in the normal force exerted on the brick?

The normal force decreases

A wave moves at a constant speed along a string. Which one of the following statements is false concerning the motion of particles in the string?

The particle speed is constant

is it possible for a large amount of force to produce little, even zero, torque

yes

In which of the following situations could an object possibly be in equilibrium (1) Three forces act on the object; the forces all point along the same line but may have different directions (2) Two perpendicular forces act on the object (3) A single force acts on the object (4) In none of the situations described above could the object possibly be in equilibrium

1

Alice and Bill, who happen to have the same mass, both want to climb to the top of a mountain. Bill wants to take the steep path straight up, but Alice wants to take the path that gently winds around the mountain, even though it is 8 times longer than the steep path. They both eventually reach the top of the mountain, but Alice reaches the top in 1/3 the time that Bill takes using the steep route. How does the work that Alice did in climbing the mountain compare with the amount that Bill did?

Alice and Bill did the same amount of work

Which one of the following statements concerning Newton's first law of motion is false?

All objects in motion have forces acting on them

Consider the situation shown in the drawing. Wave fronts of water waves approaching an aperture from the left are shown. Which of the following statements concerning this situation is true?

Because the wavelength is much smaller than the aperture, low dispersion occurs.

A block of mass M is attached to one end of a spring that has a spring constant k. The other end of the spring is attached to a wall. The block is free to slide on a frictionless floor. The block is displaced from the position where the spring is neither stretched nor compressed and released. It is observed to oscillate with a frequency f. Which one of the following actions would increase the frequency of the motion?

Decrease the mass of the block.

The picture shows a wine rack for a single bottle of wine that seems to defy common sense as it balances on a table top. Where is the center of gravity of the combined wine rack and bottle of wine?

Directly above the point where the wine rack touches the tabletop

A father and his 7-yr old daughter are facing each other on skates. With their hands they push off against one another. Which one of the following statements is (are) true?

Each experiences an acceleration that has a different magnitude

An object, which is considered a rigid body, is NOT in equilibrium. Which one of the following statements must be true concerning the angular acceleration and translational acceleration a of the object?

Either a> 0rad/s2or a>0m/s2

Engine A has a greater power rating that engine B. Which one of the following statements correctly describes the abilities of these engines to do work

Engines A and B can do the same amount of work, but engine A can do it more quickly.

The magnitude of the apparent weight of an object is the same as which if the following quantities

FN, the magnitude of the normal force acting on the object

What happens when a spinning ice skater draws in her outstretched arms?

Her moment of inertia decreases causing her to speed up

Which one of the following units is used for frequency?

Hz

A simple pendulum consists of a ball of mass m suspended from the ceiling using a string of length L. The ball is displaced from its equilibrium position by a small angle and released. Which one of the following statements concerning this situation is correct?

If the length of the pendulum were increased, the angular frequency of the pendulum would decrease.

Which one of the following statements concerning periodic waves is false?

If the periodic wave is traveling on a guitar string, its speed depends on the amplitude of the wave

A ball of mass m is attached to the end of a spring that has a spring constant k. When the ball is displaced from its equilibrium position and released, it moves in simple harmonic motion. Consider the relationship between the angular frequency, the mass, and the spring constant you just studied. Which one of the following statements concerning that relationship is true?

Increasing the spring constant causes the angular frequency to increase

A rock is thrown straight up from the earth's surface. Which one of the following statements concerning the net force acting on the rock at the top of its path is true, if air resistant can be neglected?

It is equal to the weight of the rock

A small plane increases its altitude by flying with a constant velocity at an angle Ø with respect to the horizontal. Which one of the following statements is true concerning the magnitude of the net force on the plane?

It is equal to zero newtons

Which one of the following statements most accurately describes the center of gravity of an object?

It is the point from which the torque produced by the weight of the object can be calculated.

Which one of the following choices represents the largest kinetic energy?

Mars is moving in its orbit around the Sun.

Which one of the following statements concerning the principle of the conservation of mechanical energy is true?

Mechanical energy is always conserved in situations where external non- conservative forces do no work.

Our solar system was once a cloud of interstellar gas rotating in space. Because gravitational force pulled the gas particles together, the cloud shrank, and ultimately, our Sun (a star) was formed. Would the angular velocity of the Sun be

More than the angular velocity of the rotating cloud

starting in the spring, fruit begins to grow on the outer end of a branch on a pear tree. As the fruit grows, the center of gravity of the pear- growing branch

Moves toward the pears at the end of the branch

A ball has a speed of 15 m/s. Only one external force acts on the ball. After this force acts, the speed of the ball is 7 m/s. The force does _________

Negative work

Complete the following statement: An inertial reference frame is one in which

Newton's first law of motion is valid.

A suitcase is hanging straight down from your hand as you ride an escalator. Your hand exerts a force on the suitcase, and this force does work. This work is:

Positive when you ride up; negative when you ride down

Sara carries a heavy box of books down a flight of stairs from the third floor to the first floor. Which one of the following statements best describes the work done on the box by Sara?

Sara does a large amount of negative work on the heavy box of books

Which one of the following statements best describes the concept of sound intensity?

Sound intensity is the sound power that passes perpendicularly through a surface divided by the area of that surface

Which one of the following is an example of an object with a non-zero kinetic energy?

The International Space Station orbits the Earth

An object that obeys Hooke's law is displaced a distance x by a net force. Which one of the following statements correctly describes the resulting acceleration of the object?

The acceleration increases as x increases and it decreases as x decreases

According to the Principle of Superposition, how are two waves combined to produce a resultant wave?

The amplitudes of the two waves are added algebraically.

A ball moves in a circular path on a horizontal, frictionless surface as shown. It is attached to a light string that passes through a hole in the center of the table. If the string is pulled down, thereby reducing the radius of the path of the ball, the speed of the ball is observed to increase. Which one of the following statements provides an explanation for this increase?

The angular momentum of the ball is conserved in this process

A child standing on the edge of a freely spinning merry-go-round moves quickly to the center. Which one of the following statements is necessarily true concerning this event and why?

The angular speed of the system increases because the moment of inertia of the system has decreased.

A block of mass M is attached to one end of a spring that has a spring constant k. The other end of the spring is attached to a wall. The block is free to slide on a frictionless floor. The block is displaced from the position where the spring is neither stretched nor compressed and released. It is observed to oscillate with a frequency f. Which one of the following statements is true concerning the motion of the block?

The block's acceleration is greatest when the mass has reached its maximum displacement

A force is applied to a doorknob. This force will be most effective in causing the door to rotate when which of the following is true?

The direction of the force is at an angle of 90 with respect to the door.

In which one of the following circumstances does the force do negative work on the object?

The direction of the force is in the opposite direction to the object's displacement

In which one of the following circumstances does the force do positive work on the object?

The direction of the force is in the same direction as the object's displacement

Complete the following statement: In general, the term stress refers to

a force per unit area

In which one of the following situations is zero net work done?

a horse pulls a wagon at a constant velocity

Which one of the following quantities is NOT a factor in determining the natural frequency of a string fixed at its two ends?

acceleration due to gravity

Complete the following statement: In an isolated system, the total mechanical energy remains constant if

all exerted forces are conservative

Complete the following sentence: The Principle of Linear Superposition may

be applied to all types waves.

A stack of books whose true weight is 165 N is placed on a scale in an elevator. The scale reads 165 N. From this information alone, can you tell whether the elevator is

cannot be determined

A block on a frictionless surface is attached to a horizontal spring that is stretched and released. Complete the following statement: The work done by the spring on the block

depends on the distance the spring is stretched from its relaxed position.

Complete the following statement: The net work done by a conservative force acting on an object

depends only on the starting and ending points

Complete the following statement: The net force that results when two or more forces act on an object is

determined using vector addition of the individual forces acting on the object.

Complete the following statement: When determining the net torque on a rigid body, only the torques due to

external forces are considered.

Which one of the following tools is useful in representing the forces acting on an object and simplifies problem solving?

free-body diagram

Which of the following occurs when the Doppler effect is produced by a moving source of sound?

frequency changes