Simple Harmonic Motion (College Board AP® Physics 1: Algebra-Based): Exam Questions

1 hour30 questions
1a
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1 mark

Describe the meaning of the term equilibrium position in simple harmonic motion.

1b
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1 mark

A horizontal mass-spring system oscillates with simple harmonic motion with amplitude A and period T. At t space equals space 0, the mass starts moving in the positive direction from equilibrium.

Determine the displacement of the mass when t space equals space 3 over 4 T.

1c
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1 mark

Describe the meaning of the term restoring force.

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2a
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2 marks

State two assumptions made when describing a pendulum as a simple harmonic oscillator.

2b
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1 mark

State the condition of simple harmonic motion for a simple pendulum in terms of torque.

2c2 marks

A pendulum consists of a small object of mass m connected to the bottom of a light string of length L, which is connected to a ceiling. The pendulum reaches its maximum angular displacement, theta subscript m a x end subscript.

Determine an expression for the restoring torque of the pendulum at this point. Write your expression in terms of m, L, theta and physical constants as appropriate.

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3a
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1 mark

A block is suspended from a spring attached to a ceiling. The block is initially held at rest, then set into simple harmonic motion. It completes a full cycle in time T.

Define the meaning of the term full cycle in simple harmonic motion.

3b
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1 mark

The amplitude of oscillations is doubled.

Describe how this affects the period of oscillations.

3c
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3 marks

The mass of the oscillating block is increased by a factor of 3.

Determine the factor by which the period of oscillations changes.

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4
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3 marks

Students set up an experiment with a pendulum which consists of an object with mass m on the end of a string of length l. They measure the frequency of oscillations to be f when the pendulum is displaced to an angle theta and released.

The experiment is repeated and the pendulum is displaced the same amount, but the length of string is increased. Predict how this change will affect the frequency of the oscillations. Justify your estimate using qualitative reasoning beyond referencing equations.

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5
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1 mark
A spring is attached to block P of mass m at one end and to a wall at the other end. Block P is at position x_0 and is moving left. Bock Q of mass 2m is being dropped onto block P.

Figure 1

Block P of mass m is on a horizontal, frictionless surface and is attached to a spring with spring constant k. The block is oscillating with period T subscript P and amplitude A subscript P about the spring's equilibrium position x subscript 0. A second block Q of mass 2 m is then dropped from rest and lands on block P at the instant it passes through the equilibrium position, as shown above. Block Q immediately sticks to the top of block P, and the two-block system oscillates with period T subscript P Q end subscript and amplitude A subscript P Q end subscript·

Determine the numerical value of the ratio T subscript P Q end subscript over T subscript P.

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1
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3 marks

A small mass m is attached to an ideal horizontal spring of spring constant k and is set into simple harmonic motion. The system oscillates on a frictionless surface. The mass is displaced by an initial amplitude A and released from rest. The oscillations have a period T subscript s.

Derive an expression for the maximum force exerted on the small mass by the spring. Express your answer in terms of T subscript s, m, A and physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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2
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5 marks
A cart on a horizontal spring, fixed to a wall at the other end, is held in place by a hand at position x = +L. x=0 denotes equilibrium position. x = -L is also marked on the diagram.

Figure 1

A cart on a horizontal surface is attached to a spring. The other end of the spring is attached to a wall. The cart is initially held at rest, as shown in Figure 1. When the cart is released, the system consisting of the cart and spring oscillates between the positions x space equals space plus L and x space equals space minus L.

A spring is attached to a wall and a cart of mass m_0 is attached to the other end. The cart is at position x=+L, positions x=0 and x=-L are marked. A hand is dropping a mass m onto the cart while it is at x=+L

Figure 2

When the cart is at position plus L and momentarily at rest, a block is dropped onto the cart, as shown in Figure 2. The block sticks to the cart, and the block-cart-spring system continues to oscillate between negative L and plus L. The masses of the cart and the block are m subscript 0 and m, respectively and the spring has a spring constant k.

i) The frequency of oscillation before the block is dropped onto the cart is f subscript 0. The frequency of oscillation after the block is dropped onto the cart is f. Determine an expression for the ratio f over f subscript 0.

ii) Derive an expression for the acceleration of the block-cart-spring system at position plus L. Express your answer in terms of m, m subscript 0, k and L. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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3a
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3 marks

A small block of mass m is attached to a horizontal ideal spring with a spring constant k. The block oscillates on a frictionless surface with an amplitude A. A student adds a second identical block onto the first block at maximum displacement. The new system continues oscillating. Air resistance is negligible.

Derive an expression for the new frequency of oscillation after the second block is added. Express your answer in terms of k, m, and fundamental constants.

3b
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2 marks

The period of the system is T when the additional mass is added. The additional mass is then removed, and the spring constant is halved. The period of this system is now T apostrophe.

Indicate whether T apostrophe is greater than, equal to, or less than T after the changes to the system. Justify your prediction.

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4
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4 marks

A small mass m is attached to an ideal horizontal spring of spring constant k and is set into simple harmonic motion. The system oscillates on a frictionless surface. The mass is displaced by an initial amplitude A and released from rest. It reaches maximum speed v subscript m a x end subscript and maximum acceleration a subscript m a x end subscript. The motion follows the equation:

x space equals space A cos open parentheses 2 pi f t close parentheses

where f is the frequency of oscillation.

A second identical system is made to oscillate in the same way at the same time, but this system experiences a constant friction force. After 10 s, this system has maximum acceleration a subscript m a x comma f end subscript. Indicate whether a subscript m a x comma f end subscript is greater than, less than or equal to a subscript m a x end subscript.

bottom enclose space space space space space space space space space space space space space space space space space end enclose a subscript m a x comma f end subscript greater than a subscript m a x end subscript bottom enclose space space space space space space space space space space space space space space space space space end enclose a subscript m a x comma f end subscript less than a subscript m a x end subscript bottom enclose space space space space space space space space space space space space space space space space space end enclose a subscript m a x comma f end subscript equals a subscript m a x end subscript

Justify your answer.

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5
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3 marks

An object of mass m rests on a horizontal surface and is attached to the end of a light, ideal spring of spring constant k. The other end of the spring is attached to a vertical rigid wall.

Derive an expression for the acceleration of the object in the x direction when it is displaced a distance straight capital delta x from equilibrium, in terms of k, m and straight capital delta xand physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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11 mark
Spring attached to ceiling holds a mass. The mass lies 1.00 m above a motion detector.

Figure 1

A spring of unknown spring constant k subscript 0 is attached to a ceiling. A lightweight hanger is attached to the lower end of the spring, and a motion detector is placed on the floor facing upward directly under the hanger, as shown in the figure above. The bottom of the hanger is 1.00 m above the motion detector.

An object of mass m is then placed on the hanger and allowed to come to rest at the equilibrium position, such that the bottom of the hanger is distance d below its initial position. The spring is then stretched downward from equilibrium and released at time t = 0 s. The motion detector records the height of the bottom of the hanger as a function of time. The output from the motion detector is shown in Figure 2.

Graph of a sine wave showing oscillation of height in centimetres against time in seconds, with equilibrium position at 60 cm highlighted.

Figure 2

i) On Figure 3 below, sketch a free body diagram of the object at equilibrium.

6 x 8 grid

Figure 3

ii) Determine an expression for k subscript 0 in terms of m, d and physical constants as appropriate.

iii) Starting with the equation for the period of a mass on a spring, derive an expression for the frequency of the object on the spring in terms of d and physical constants as appropriate.

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2
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4 marks
Spring 1 has constant k_1. It is in series with spring 2, with constant k_2. This is connected to a block with mass m. The block is to the left of equilibrium at x = -A, such that the springs are compressed.

Figure 1

Two ideal springs, 1 and 2, of spring constant k subscript 1 and k subscript 2 respectively, are connected end to end. A block of mass m is attached to the end of Spring 2 and the other end of Spring 1 is fixed to a wall. The block is displaced to the left of the spring's equilibrium position, x space equals space 0, and held stationary at position x space equals space minus A, as shown in Figure 1. The block is then released at time t space equals space 0.

At time t space equals space t subscript 0, the block's displacement is x space equals space 1 half A and it is travelling to the right.

i) Derive an expression for the effective spring constant of Spring 1 and Spring 2 in terms of k subscript 1, k subscript 2 and physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

ii) Starting with the equation for the displacement of an object in simple harmonic motion, derive an expression for time t subscript 0 in terms of k subscript 1, k subscript 2, m and physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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3
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7 marks
A pendulum of length R with a mass m at an angle θ to the vertical

Figure 1

A pendulum is displaced to angle theta before being released. Upon being released, the pendulum has angular acceleration alpha subscript 0. The string has length R and the bob at the end has mass m.

i) On the diagram in Figure 1, draw and label arrows that represent the forces (not components) that are exerted on the pendulum bob. Each force in your diagram must be represented by a distinct arrow starting on, and pointing away from, the point at which the force is exerted on the bob.

ii) Determine an expression for the tangential acceleration of the pendulum the moment it is released in terms of theta and physical constants as appropriate.

iii) Derive an expression for the period of this pendulum. Express your answer in terms of alpha subscript 0, theta and physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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4
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3 marks
Two images. In one, a black of mass m is held 1 m above a motion detector. A single spring with constant k is attached between the block and the ceiling. This image is labeled N=1. The second image is identical, but there are two springs, both with spring constant k. This image is labeled N=2.

Figure 1

A student conducts an investigation to determine the relationship between the period of oscillation T of a system consisting of a block and N attached springs. The student starts with a block of mass m attached to a single ideal spring of spring constant k, as shown in the first diagram in Figure 1. The student holds the block so that the spring is neither stretched nor compressed at a vertical height 1.00 m above a motion detector. The student releases the block from rest and records the period of oscillation for the system consisting of the single spring and block. An additional identical spring is attached in parallel, as shown in the second diagram in Figure 1, and the procedure is repeated for N equals 2 springs. This procedure is repeated through N equals 10 springs.

Derive an expression for T as a function of N. Express your answer in terms of m, k, N, and physical constants as appropriate. Begin your derivation by writing a fundamental physics principle or an equation from the reference information.

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5a
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1 mark
Two images. In one, a black of mass m is held 1 m above a motion detector. A single spring with constant k is attached between the block and the ceiling. This image is labeled N=1. The second image is identical, but there are two springs, both with spring constant k. This image is labeled N=2.

Figure 1

A student conducts an investigation to determine the relationship between the period of oscillation T of a system consisting of a block and N attached springs. The student starts with a block of mass m attached to a single ideal spring of spring constant k, as shown in the first diagram in Figure 1. The student holds the block so that the spring is neither stretched nor compressed at a vertical height 1.00 m above a motion detector. The student releases the block from rest and records the period of oscillation for the system consisting of the single spring and block. An additional identical spring is attached in parallel, as shown in the second diagram in Figure 1, and the procedure is repeated for N equals 2 springs. This procedure is repeated through N equals 10 springs.

Graph with y axis of T^2 from 0 to 12 and x axis of N^-1 from 0 to 1.1. Data points are: (0.16,2), (0.2,2.1), (0.25, 2.9), (0.33,4.1), (0.5,5.7) and (1.0,11.8)

Figure 2

The student plots the data for T squared as a function of N to the power of negative 1 end exponent as shown in Figure 2.

Draw the best-fit line for the data.

5b
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3 marks

The students determine the relationship between T and N to be:

T space equals space 2 pi square root of fraction numerator m over denominator N k end fraction end root

The mass of the block is measured to be m space equals space 1.5 space kg. Using the graph, calculate an experimental value for the spring constant k for a single spring.

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