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A heavy particle is tied to the end \(A\) of a string of length \(1.6 \mathrm{~m}\). Its other end \(O\) is fixed. It revolves as a conical pendulum with the string making \(60^{\circ}\) with the vertical. Then (1) its period of revolution is \(4 \pi / 7 \mathrm{~s}\). (2) the tension in the string is doubled the weight of the particle (3) the velocity of the particle \(=2.8 \sqrt{3} \mathrm{~m} / \mathrm{s}\) (4) the centripetal accelcration of the particle is \(9.8 \sqrt{3} \mathrm{~m} / \mathrm{s}^{2}\).

Short Answer

Expert verified
All statements (1), (2), (3), and (4) are correct.

Step by step solution

01

Understand the Geometry

The particle moves as a conical pendulum, which means it revolves in a horizontal circle while the string stays at an angle of \(60^{\circ}\) with the vertical. The string length is \(1.6 \text{ m}\). From the geometry, the radius \(r\) of the circular path is \(r = 1.6 \sin 60^{\circ} = 1.6 \times \frac{\sqrt{3}}{2} = 0.8\sqrt{3} \text{ m}\).
02

Calculate the Period of Revolution

The particle revolves in a circle, and we need to find the period \(T\). We use the centripetal force equation: \( T = 2\pi \sqrt{\frac{L \cos \theta}{g}} \). Given \(\theta = 60^{\circ}, g = 9.8 \text{ m/s}^2\), and \(L = 1.6 \text{ m}\), substitute to get: \[ T = 2\pi \sqrt{\frac{1.6 \times \cos 60^{\circ}}{9.8}} = 2\pi \sqrt{\frac{1.6 \times 0.5}{9.8}} = \frac{4\pi}{7} \text{ s}.\]
03

Determine the Tension in the String

The tension \(T_0\) must balance the components of gravitational and centripetal forces. For vertical equilibrium: \(T_0 \cos 60^{\circ} = mg\). Therefore, \[ T_0 = \frac{mg}{\cos 60^{\circ}} = 2mg + \text{(since } \cos 60^{\circ} = 0.5 \text{)}.\]
04

Find the Velocity of Particle

Velocity \(v\) is found using the centripetal force relation \(T_0 \sin 60^{\circ} = \frac{mv^2}{r}\). Substituting for \( T_0 \) and simplifying, \( 2mg \times \frac{\sqrt{3}}{2} = \frac{mv^2}{0.8\sqrt{3}} \) and solving for \( v \): \( v = 2.8\sqrt{3} \text{ m/s}.\)
05

Calculate the Centripetal Acceleration

The centripetal acceleration \( a_c \) is given by \( a_c = \frac{v^2}{r} \). Using \( v = 2.8\sqrt{3} \text{ m/s} \) and \( r = 0.8\sqrt{3} \text{ m} \), \[ a_c = \frac{(2.8\sqrt{3})^2}{0.8\sqrt{3}} = 9.8\sqrt{3} \text{ m/s}^2.\]

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Key Concepts

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

Centripetal Acceleration
In a conical pendulum, centripetal acceleration plays a vital role in keeping the particle moving in its circular path. Centripetal acceleration refers to the acceleration that acts towards the center of the circle, keeping the particle in its rotational motion. It is always perpendicular to the velocity of the particle. In mathematical terms, centripetal acceleration \( a_c \) is calculated using the formula:\[a_c = \frac{v^2}{r}\]where \( v \) is the velocity of the particle, and \( r \) is the radius of the circular path. In the context of our problem, with a velocity \( v = 2.8\sqrt{3} \text{ m/s} \) and a radius \( r = 0.8\sqrt{3} \text{ m} \), the centripetal acceleration works out to be \( 9.8\sqrt{3} \text{ m/s}^2 \). This acceleration is crucial, as it ensures the particle maintains its steady circular motion without deviating from the path.
Tension in the String
Tension in the string of a conical pendulum ensures both the vertical and horizontal components of motion are balanced. Tension \( T_0 \) is a force that acts along the string and is crucial for maintaining the system's equilibrium. In our conical pendulum setup, the tension provides the necessary centripetal force needed to keep the particle moving in a circle while also balancing the gravitational force acting on the particle.
  • Vertical Balance: The vertical component of tension must equal the gravitational force. This is expressed as \( T_0 \cos 60^{\circ} = mg \), solving this gives \( T_0 = 2mg \).
  • Horizontal Force: Part of the tension provides the centripetal force that enables circular motion. This is expressed as \( T_0 \sin 60^{\circ} \).
This means the tension in the string is twice the weight of the particle, ensuring the forces balance out perfectly to sustain the conical pendulum's motion.
Period of Revolution
The period of revolution \( T \) describes how long it takes for the particle to complete one full circle. This is a fundamental aspect of rotational motion, as it defines the overall timing of the particle's path. For a conical pendulum, the period of revolution is derived using the characteristics of the pendulum's length, the gravitational force acting on it, and the angle formed with the vertical.The formula for the period \( T \) is:\[T = 2\pi \sqrt{\frac{L \cos \theta}{g}}\]where \( L = 1.6 \text{ m} \) is the string length, \( \theta = 60^{\circ} \) is the angle, and \( g = 9.8 \text{ m/s}^2 \) is the acceleration due to gravity. Plugging in these values in the formula yields a period of \( \frac{4\pi}{7} \text{ s} \). The period is vital because it conveys the speed at which the pendulum completes its circular path, reflecting the nature of rotational dynamics within the system.
Velocity of Particle
Within a conical pendulum, understanding the velocity of the particle is key to analyzing its motion. Velocity in circular motion is a measure of how fast the particle moves along its circular path. In the case of our exercise, this velocity is derived from both the tension in the string and the need for centripetal force.The velocity \( v \) can be calculated through the relationship involving tension:\[T_0 \sin 60^{\circ} = \frac{mv^2}{r}\]Solving this equation, we find that the velocity of the particle is \( v = 2.8\sqrt{3} \text{ m/s} \). This speed indicates how quickly the particle is traversing its circular path, and it's determined by the balance of forces in the system. This existent velocity ensures that the particle stays in motion in a stable and predictable manner, aligning with the principles of rotational dynamics.

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Most popular questions from this chapter

A particle moves in a circle uniformly such that it completes a circle in \(2 \mathrm{sec}\). During half a turn its centripetal acceleration change by \(6 \mathrm{~m} / \mathrm{s}^{2}\). Choose the correct option(s). (1) the radius of the circle is \(\left(3 / \pi^{2}\right) \mathrm{m}\). (2) the magnitude of change in velocity during \(1 \mathrm{~s}\) is \(3 / \pi \mathrm{m} / \mathrm{s}\) (3) the tangential velocity of the particle is \(3 / \pi \mathrm{m} / \mathrm{s}\). (4) the particle is moving in anticlockwise sense as seen from above.

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A particle is moving along a circular path. The angul:d velocity, linear velocity, angular acceleration, and centripetal acceleration of the particle at any instant, respectively, ari \(\vec{\omega}, \vec{v}, \vec{\alpha}\), and \(\vec{a}_{c^{*}}\) Which of the following relations is noid correct? (1) \(\vec{\omega} \perp \vec{v}\) (2) \(\vec{\omega} \perp \vec{\alpha}\) (3) \(\vec{\omega} \perp \vec{\alpha}_{c}\) (4) \(\vec{v} \perp \vec{\alpha}_{c}\)

Two identical particics we string which passes through a hole at the center of a table of the particles is made to move in a circle on that string which passes througit One of the particles is made to move in a circle on the tabl with angular velocity \(\omega\), and the other is made to \(\mathrm{m}\), in a horizontal circle as a contact pendulum with angular velocity pendulum with angular velocity \(\omega_{2} .\) If \(l_{1}\) and \(l_{2}\) are the length of he string over and under the able, then in order that particle under the table neither moves own nor moves up, the ratio \(l_{1} / l_{2}\) is (1) \(\frac{\omega_{1}}{\omega_{2}}\) (2) \(\frac{\omega_{2}}{\omega_{1}}\) (3) \(\frac{\omega_{1}^{2}}{\omega_{2}^{2}}\) (4) \(\frac{\omega_{2}^{2}}{\omega_{1}^{2}}\)

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