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Ch 14: Periodic Motion
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610Not the one you use?Change textbook
Chapter 14, Problem 16b

A small block is attached to an ideal spring and is moving in SHM on a horizontal, frictionless surface. When the amplitude of the motion is 0.090 m, it takes the block 2.70 s to travel from x = 0.090 m to x = -0.090 m. If the amplitude is doubled, to 0.180 m, how long does it take the block to travel from x = 0.090 m to x = -0.090 m?

Verified step by step guidance
1
Understand that the block is undergoing Simple Harmonic Motion (SHM), which is characterized by oscillations around an equilibrium position. The time taken for one complete cycle is the period of the motion.
Recall that the period of SHM is independent of the amplitude. The period \( T \) is given by \( T = \frac{2\pi}{\omega} \), where \( \omega \) is the angular frequency.
Given that the block takes 2.70 s to travel from \( x = 0.090 \) m to \( x = -0.090 \) m, this time represents half of the period, as it covers half of the oscillation cycle.
Since the period is independent of amplitude, doubling the amplitude to 0.180 m does not change the period. Therefore, the time to travel from \( x = 0.090 \) m to \( x = -0.090 \) m remains the same.
Conclude that the time taken for the block to travel from \( x = 0.090 \) m to \( x = -0.090 \) m is still 2.70 s, even if the amplitude is doubled.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Simple Harmonic Motion (SHM)

Simple Harmonic Motion describes the oscillatory motion of an object where the restoring force is directly proportional to the displacement from its equilibrium position. In SHM, the motion is sinusoidal, characterized by a constant frequency and amplitude, and is often exemplified by systems like a mass-spring system or a pendulum.
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Amplitude in SHM

Amplitude in SHM refers to the maximum displacement of the object from its equilibrium position. It is a measure of the energy in the system, with larger amplitudes indicating more energy. In the context of the problem, changing the amplitude affects the total energy but does not alter the period of the motion, as the period is independent of amplitude in ideal SHM.
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Period and Frequency in SHM

The period in SHM is the time taken for one complete cycle of motion, while frequency is the number of cycles per unit time. For a mass-spring system, the period is determined by the mass and the spring constant, and is independent of amplitude. Thus, even if the amplitude changes, the time taken for specific displacements remains constant, as the period does not change.
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Related Practice
Textbook Question

A 0.400-kg object undergoing SHM has ax = -1.80 m/s2 when x = 0.300 m. What is the time for one oscillation?

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Textbook Question

A small block is attached to an ideal spring and is moving in SHM on a horizontal, frictionless surface. When the amplitude of the motion is 0.090 m, it takes the block 2.70 s to travel from x = 0.090 m to x = -0.090 m. If the amplitude is doubled, to 0.180 m, how long does it take the block to travel from x = 0.180 m to x = -0.180 m?

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Textbook Question

A 0.500kg0.500\(\operatorname{kg}\) mass on a spring has velocity as a function of time given by vx(t)=(3.60cm/s)sin[(4.7 rad/s)t(π/2)]v_{x}(t)=-(3.60\(\operatorname{cm}\)/s)\(\sin\)[(4.7\(\text{ }\)rad/s)t-(\(\pi\)/2)]. What are the period and the force constant of the spring?

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Textbook Question

A 2.00-kg, frictionless block is attached to an ideal spring with force constant 300 N/m. At t = 0 the spring is neither stretched nor compressed and the block is moving in the negative direction at 12.0 m/s. Find (a) the amplitude and (b) the phase angle. (c) Write an equation for the position as a function of time.

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Textbook Question

Weighing Astronauts. This procedure has been used to 'weigh' astronauts in space: A 42.5-kg chair is attached to a spring and allowed to oscillate. When it is empty, the chair takes 1.30 s to make one complete vibration. But with an astronaut sitting in it, with her feet off the floor, the chair takes 2.54 s for one cycle. What is the mass of the astronaut?

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Textbook Question

The point of the needle of a sewing machine moves in SHM along the x-axis with a frequency of 2.5 Hz. At t = 0 its position and velocity components are +1.1 cm and -15 cm/s, respectively. Find the acceleration component of the needle at t = 0.

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