Physics test 3

1) Two forces produce equal torques on a door about the door hinge. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force has a greater magnitude? A) the first force (at the midpoint) B) the second force (at the doorknob) C) The two forces are equal.

A

11) If the amplitude of the motion of a simple harmonic oscillator is doubled, by what factor does the maximum speed of the oscillator change? A) 2 B) 4 C) It does not change. D) 1/2 E) 1/4

A

3) A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneously at the top of an inclined plane and do not slip, which one will reach the bottom first? A) sphere B) pipe C) cylinder D) The pipe and cylinder arrive together before the sphere. E) They all reach the bottom at the same time.

A

37) A mass is attached to a vertical spring and bobs up and down between points A and B. Where is the mass located when its kinetic energy is a maximum? A) midway between A and B B) one third of the way between A and B C) one fourth of the way between A and B D) at either A or B E) none of the above

A

4) An object is attached to a vertical spring and bobs up and down between points A and B. Where is the object located when its kinetic energy is a minimum? A) at either A or B B) midway between A and B C) one-third of the way between A and B D) one-fourth of the way between A and B E) at none of the above points

A

For periodic motion, the maximum displacement from the equilibrium point is called the 33) A) amplitude. B) energy. C) period. D) wavelength. E) frequency.

A

Four waves are described by the following equations, where distances are measured in meters and times in seconds. I.y= 0.12 cos(3x- 21t) II. y= 0.15 sin(6x+ 42t) III.y= 0.13 cos(6x+ 21t) IV.y = -0.23 sin(3x- 42t) Which of these waves have the same speed?

A

On the Moon, the acceleration of gravity is g/6. If a pendulum has a period T on Earth, what will its period be on the Moon? A) Tsqrt6 B) T/6 C) T/sqrt6 D) 6T E) T/3

A

The time for one cycle of a periodic process is called the A) period. B) energy. C) wavelength. D) amplitude. E) frequency

A

Two children are riding on a merry - go - round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger linear displacement? 5) A) Child A B) Child B C) They have the same zero linear displacement. D) They have the same non -zero linear displacement. E) There is not enough information given to answer the question

A

Two children are riding on a merry - go - round. Child A is at a greater distance from the axis of rotation than child B. Which child has the larger tangential acceleration? 6) A) Child A B) Child B C) They have the same non -zero centripetal acceleration. D) They have the same zero centripetal acceleration. E) There is not enough information given to answer the question

A

mass is attached to a spring and oscillates with a period T . If the mass is doubled, what is the new period? 34) A) Tsqrt2 B) 2T C) T/sqrt2 D) T/2 E) T

A

wo balls, one of radius R and mass M, the other of radius 2 R and mass 8 M, roll down an incline. They start together from rest at the top of the incline. Which one will reach the bottom of the incline first? 8) A) Both reach the bottom together. B) The large sphere C) The small sphere D) It depends on the height of the incline. E) It depends on the length of the inclined surface

A

2) Consider a solid uniform sphere of radius R and mass M rolling without slipping. Which form of its kinetic energy is larger, translational or rotational? A) Translational kinetic energy is larger. B) Rotational kinetic energy is larger. C) Both are equal. D) You need to know the speed of the sphere to tell.

A.

2) A string of mass m is under tension, and the speed of a wave in the string is v . What will be the speed of a wave in the string if the mass of the string is increased to 2 m but with no change in the length or tension? A) v/2 B) v/sqrt2 C) vsqrt2 D) 2v E) 4v

B

22) Angular momentum cannot be conserved if A) the moment of inertia changes. B) the net torque is not zero. C) the angular acceleration changes. D) the angular velocity changes. E) there is a net force on the system

B

30) A person sits on a freely spinning lab stool (no friction). When this person extends her arms, A) her moment of inertia decreases and her angular velocity increases. B) her moment of inertia increases and her angular velocity decreases. C) her moment of inertia increases and her angular velocity increases. D) her moment of inertia increases and her angular velocity remains the same. E) her moment of inertia decreases and her angular velocity decreases

B

9) A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They all roll without slipping. In what order do they reach the bottom? A) hoop, sphere, disk B) sphere, disk, hoop C) hoop, sphere, disk D) disk, hoop, sphere E) hoop, disk, sphere

B

A pendulum of length L is suspended from the ceiling of an elevator. When the elevator is at rest the period of the pendulum is T . How does the period of the pendulum change when the elevator moves downward with constant acceleration? A) The period decreases. B) The period increases. C) The period becomes zero. D) The period does not change. E) The period decreases if the downward acceleration is more than g/2 but increases if the downward acceleration is less than g/2.

B

The total mechanical energy of a simple harmonic oscillator is 36) A) zero as it passes the equilibrium point. B) constant. C) a maximum when it passes through the equilibrium point. D) a minimum when it passes through the equilibrium point. E) zero when it reaches the maximum displacement.

B

Two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque? 31) A) both exert equal non - zero torques B) the second at the doorknob C) the first at the midpoint D) both exert zero torques E) Additional information is needed.

B

4) If the answer to your calculation has units of kg ∙ m2/s2, what type of quantity could it be? (There could be more than one correct choice.) A) force B) work C) angular momentum D) linear momentum E) power F) rotational kinetic energy G) moment of inertia H) torque

B, F, H

An object that hangs from the ceiling of a stationary elevator by an ideal spring oscillates with a period T . If the elevator accelerates upward with acceleration 2 g , what will be the period of oscillation of the object? A) 4T B) 2T C)T D) T/2 E) T/4

C

19) A ball is attached to an ideal spring and oscillates with a period T . If the mass of the ball is doubled, what is the new period? A) 2T B) T /2 C) T D) Tsqrt2 E) T/sqrt2

D

4) The intensity of the waves from a point source at a distance d from the source is I . What is the intensity at a distance 2 d from the source? A) 4I B) 2I C)I/2 D)I/4 E)I/sqrt2

D

7) In a resonating pipe that is open at one end and closed at the other end, there A) are displacement nodes at each end. B) are displacement antinodes at each end. C) is a displacement node at the open end and a displacement antinode at the closed end. D) is a displacement node at the closed end and a displacement antinode at the open end.

D

A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms, A) her moment of inertia decreases and her angular speed increases. B) her moment of inertia decreases and her angular speed decreases. C) her moment of inertia increases and her angular speed increases. D) her moment of inertia increases and her angular speed decreases. E) her moment of inertia increases and her angular speed remains the same.

D

A solid cylinder is rolling without slipping. What fraction of its kinetic energy is rotational? A) 2/3 B) 3/4 C) 1/4 D) 1/3 E) 1/2

D

3) The total mechanical energy of a simple harmonic oscillating system is A) zero as it passes the equilibrium point. B) zero when it reaches the maximum displacement. C) a maximum when it passes through the equilibrium point. D) a minimum when it passes through the equilibrium point. E) a non-zero constant.

E

Doubling only the mass of a vibrating mass and spring system produces what effect on the system's mechanical energy? A) increases the energy by a factor of two B) increases the energy by a factor of four C) increases the energy by a factor of square root of two D) increases the energy by a factor of three E) produces no change

E

If the frequency of the motion of a simple harmonic oscillator is doubled, by what factor does the maximum speed of the oscillator change? A)4 B)1/4 C)1/2 D)1 E)2

E

Two strings are made of the same material. String 1 has radius r1 while string 2 has radius r2=r1/2. When stretched by the same tension, the respective speed of propagation of waves v1 and v2 satisfy the condition A) v1=v2/2 . B) v1=2v2 . C)v1=v2/4. D) v 1 = 2 v 2 . E) v 1 = v 2 /2

E

When you ride a bicycle, in what direction is the angular velocity of the wheels? A) to your right B) forwards C) up D) backwards E) to your left

E

A wave pulse on a string whose end is fixed is reflected without inversion.

F

Sound waves in air are transverse waves

F

TRUE OR FALSE When a rigid body rotates about a fixed axis all the points in the body have the same tangential speed

F

When a rigid body rotates about a fixed axis all the points in the body have the same centripetal acceleration.

F

Five forces act on a rod that is free to pivot at point P, as shown in the figure. Which of these forces is producing a counter-clockwise torque about point P? (There could be more than one correct choice.)

FORCE C

1) When a rigid object rotates about a fixed axis, what is true about all the points in the object? (There could be more than one correct choice.) A) They all have the same angular speed. B) They all have the same tangential speed. C) They all have the same angular acceleration. D) They all have the same tangential acceleration. E) They all have the same radial acceleration.

a. they all have the same angular speed c. they all have the same angular acceleration

1) If we double the frequency of a system undergoing simple harmonic motion, which of the following statements about that system are true? (There could be more than one correct choice.) A) The period is doubled. B) The angular frequency is doubled. C) The amplitude is doubled. D) The period is reduced to one-half of what it was. E) The angular frequency is reduced to one-half of what it was.

b and d