A massive object of \(m=5.00 \mathrm{~kg}\) oscillates with simple harmonic motion. Its position as a function of time varies according to the equation \(x(t)=2 \sin ([\pi / 2] t+\pi / 6)\). a) What is the position, velocity, and acceleration of the object at \(t=0 \mathrm{~s}^{2}\) b) What is the kinetic energy of the object as a function of time? c) At which time after \(t=0 \mathrm{~s}\) is the kinetic energy first at a maximum?

Short Answer

Expert verified
Question: Find the position, velocity, and acceleration functions for an object undergoing simple harmonic motion, along with the position, velocity, and acceleration at t=0s. Also, find the kinetic energy function and the first time the kinetic energy reaches its maximum value after t=0s. Answer: The position function is given by: \(x(t) = 2 \sin (\frac{\pi}{2} t + \frac{\pi}{6})\) The velocity function is: \(v(t) = \pi \cos (\frac{\pi}{2} t + \frac{\pi}{6})\) The acceleration function is: \(a(t) = - \frac{\pi^2}{2} \sin (\frac{\pi}{2} t + \frac{\pi}{6})\) At t=0s: Position: \(x(0) = 2 \sin (\frac{\pi}{6}) = 1 \mathrm{~m}\) Velocity: \(v(0) = \pi \cos (\frac{\pi}{6}) = \frac{\pi \sqrt{3}}{2} \mathrm{~m/s}\) Acceleration: \(a(0) = - \frac{\pi^2}{2} \sin (\frac{\pi}{6}) = -\frac{\pi^2}{2} \mathrm{~m/s^2}\) The kinetic energy function is: \(K.E.(t) = \frac{5 \pi^2}{4} \cos^2(\frac{\pi}{2} t + \frac{\pi}{6})\) The first time the kinetic energy reaches its maximum value is at approximately \(t = 0.81\mathrm{~s}\).

Step by step solution

01

Find the velocity function and the acceleration function

Differentiate the position function \(x(t)\) with respect to time \(t\) to get the velocity function \(v(t)\), and then differentiate the velocity function to get the acceleration function \(a(t)\). \(x(t) = 2 \sin (\frac{\pi}{2} t + \frac{\pi}{6})\) \(v(t) = \frac{d}{dt}(2 \sin (\frac{\pi}{2} t + \frac{\pi}{6}))\) \(a(t) = \frac{d^2}{dt^2}(2 \sin (\frac{\pi}{2} t + \frac{\pi}{6}))\)
02

Calculate position, velocity, and acceleration at \(t=0 \mathrm{~s}\)

Plug in \(t=0\) into the position, velocity, and acceleration functions to find the values at \(t=0 \mathrm{~s}\). \(x(0) = 2 \sin (\frac{\pi}{2} \cdot 0 + \frac{\pi}{6})\) \(v(0) = v(0)\) (calculated in step 1) \(a(0) = a(0)\) (calculated in step 1)
03

Find the kinetic energy function

Using the kinetic energy formula \(K.E. = \frac{1}{2}mv^2\), plug in the mass \(m=5\mathrm{~kg}\) and the velocity function \(v(t)\) to find the kinetic energy function. \(K.E.(t) = \frac{1}{2}(5\mathrm{~kg})(v(t))^2\)
04

Calculate the first time the kinetic energy reaches its maximum value

To find the first time the kinetic energy is at a maximum, we need to find the critical points of the kinetic energy function by setting the derivative of the kinetic energy function with respect to time equal to zero. Solve for the time \(t\), making sure to find the first maximum after \(t=0 \mathrm{~s}\). \(\frac{d}{dt}(K.E.(t)) = 0\) Solving for \(t\) gives us the time at which the kinetic energy first reaches its maximum value.

Unlock Step-by-Step Solutions & Ace Your Exams!

  • Full Textbook Solutions

    Get detailed explanations and key concepts

  • Unlimited Al creation

    Al flashcards, explanations, exams and more...

  • Ads-free access

    To over 500 millions flashcards

  • Money-back guarantee

    We refund you if you fail your exam.

Over 30 million students worldwide already upgrade their learning with Vaia!

Key Concepts

These are the key concepts you need to understand to accurately answer the question.

Kinetic Energy
Kinetic energy is the energy that an object possesses due to its motion. It is defined as half the product of the mass times the velocity squared. For an object of mass 'm', moving with velocity 'v', the kinetic energy 'KE' is given by the formula:\[\begin{equation} KE=\frac{1}{2}mv^2 \right).\frac{1}{2}mv^2\end{equation}\]In the context of simple harmonic motion (SHM), the velocity of the object changes constantly as it oscillates back and forth. As a result, the kinetic energy also varies with time. For a comprehensive understanding, let's consider a mass on a spring, when the mass passes through the equilibrium position, it's at maximum velocity, and consequently, it has maximum kinetic energy. Conversely, at the turning points, the velocity is zero, making the kinetic energy zero as well.
Oscillatory Motion
Oscillatory motion refers to a movement that repeatedly follows a specific path in a regular time interval, back and forth around an equilibrium position. A classic example is a pendulum or a mass-spring system engaging in simple harmonic motion, which is a type of oscillatory motion characterized by a sinusoidal wave with constant amplitude and period.

In SHM, all points along the path have a defined kinetic and potential energy, which transforms into each other while conserving the total mechanical energy of the system. An object in SHM follows a predictable restoration force proportional to its displacement from the equilibrium position, often described by Hooke's law when dealing with a spring.
Differentiation in Physics
Differentiation is a fundamental concept in calculus, often used in physics to determine how a quantity changes over time. When applied to motion, it enables us to find velocity and acceleration from the position function. Here's how it works:
  • The velocity of an object is the rate of change of its position with respect to time, which we find by differentiating the position function once.
  • Similarly, the acceleration is the rate of change of the velocity with respect to time, so we get it by differentiating the velocity function.
It's pivotal to understand differentiation when evaluating the behavior of systems in motion, like our SHM example, since these values are critical for establishing the kinetic energy and the nature of the motion over time.
Velocity and Acceleration
Velocity and acceleration are integral parts of analyzing motion. Velocity is a vector quantity that denotes the rate of change of an object's position, indicating both how fast it's moving and in what direction. Acceleration, also a vector quantity, communicates how the velocity of the object changes over time.

During simple harmonic motion, velocity and acceleration are at their maximums when the object crosses the equilibrium position and at their minimums (zero) at the maximum displacements. These two quantities are out of phase in SHM; when one is zero, the other is at a maximum or minimum. This relationship is pivotal as it directly influences the kinetic energy of the system, revealing the dynamic nature of objects in oscillatory motion.

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

A horizontal tree branch is directly above another horizontal tree branch. The elevation of the higher branch is \(9.65 \mathrm{~m}\) above the ground, and the elevation of the lower branch is \(5.99 \mathrm{~m}\) above the ground. Some children decide to use the two branches to hold a tire swing. One end of the tire swing's rope is tied to the higher tree branch so that the bottom of the tire swing is \(0.47 \mathrm{~m}\) above the ground. This swing is thus a restricted pendulum. Start. ing with the complete length of the rope at an initial angle of \(14.2^{\circ}\) with respect to the vertical, how long does it take a child of mass \(29.9 \mathrm{~kg}\) to complete one swing back and forth?

A spring is hanging from the ceiling with a mass attached to it. The mass is pulled downward, causing it to oscillate vertically with simple harmonic motion. Which of the following will increase the frequency of oscillation? a) adding a second, identical spring with one end attached to the mass and the other to the ceiling b) adding a second, identical spring with one end attached to the mass and the other to the floor c) increasing the mass d) adding both springs, as described in (a) and (b)

A mass \(M=0.460 \mathrm{~kg}\) moves with an initial speed \(v=3.20 \mathrm{~m} / \mathrm{s}\) on a level frictionless air track. The mass is initially a distance \(D=0.250 \mathrm{~m}\) away from a spring with \(k=\) \(840 \mathrm{~N} / \mathrm{m}\), which is mounted rigidly at one end of the air track. The mass compresses the spring a maximum distance \(d\), before reversing direction. After bouncing off the spring the mass travels with the same speed \(v\), but in the opposite dircction. a) Determine the maximum distance that the spring is compressed. b) Find the total elapsed time until the mass returns to its starting point. (Hint: The mass undergoes a partial cycle of simple harmonic motion while in contact with the spring.)

When the amplitude of the oscillation of a mass on a stretched string is increased, why doesn't the period of oscil lation also increase?

A small mass, \(m=50.0 \mathrm{~g}\), is attached to the end of a massless rod that is hanging from the ceiling and is free to swing. The rod has length \(L=1.00 \mathrm{~m} .\) The rod is displaced \(10.0^{\circ}\) from the vertical and released at time \(t=0\). Neglect air resistance. What is the period of the rod's oscillation? Now suppose the entire system is immersed in a fluid with a small damping constant, \(b=0.0100 \mathrm{~kg} / \mathrm{s},\) and the rod is again released from an initial displacement angle of \(10.0^{\circ}\). What is the time for the amplitude of the oscillation to reduce to \(5.00^{\circ}\) ? Assume that the damping is small Also note that since the amplitude of the oscillation is small and all the mass of the pendulum is at the end of the rod, the motion of the mass can be treated as strictly linear, and you can use the substitution \(R \theta(t)=x(t),\) where \(R=1.0 \mathrm{~m}\) is the length of the pendulum rod.

See all solutions

Recommended explanations on Physics Textbooks

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free