/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 12 A torque equal to \(\left(\frac{... [FREE SOLUTION] | 91Ó°ÊÓ

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A torque equal to \(\left(\frac{5}{\pi}\right) \times 10^{-6} \mathrm{Nm}\) acting on a body produces 2 revolutions per second, then the rotational power expended is: (a) \(\frac{1}{\pi} \times 10^{-5} \mathrm{~J} / \mathrm{s}\) (b) \(2 \times 10^{-\bar{j}} \mathrm{~J} / \mathrm{s}\) (c) \(2.5 \pi \times 10^{-6} \mathrm{~J} / \mathrm{s}\) (d) \(\frac{2 \pi}{5} \times 10^{-8} \mathrm{~J} / \mathrm{s}\)

Short Answer

Expert verified
The rotational power expended is 2.0 x 10^{-5} J/s, option (b).

Step by step solution

01

Understand the Problem

We are given a torque of \( \frac{5}{\pi} \times 10^{-6} \) Nm and the body makes 2 revolutions per second. We need to find the rotational power expended, which is the product of torque and angular velocity.
02

Calculate Angular Velocity

Since 1 revolution corresponds to an angular distance of \(2\pi\) radians, an angular velocity of 2 revolutions per second is equivalent to \(2 \times 2\pi = 4\pi\) radians per second.
03

Calculate the Rotational Power

Rotational power (\(P\)) is given by the formula \(P = \text{Torque} \times \text{Angular Velocity}\). Substituting the given values, \(P = \left(\frac{5}{\pi} \times 10^{-6} \text{ Nm}\right) \times 4\pi \text{ rad/s}\).
04

Simplify the Expression

Simplify the power expression: \(P = \frac{5}{\pi} \times 10^{-6} \times 4\pi = 5 \times 4 \times 10^{-6} = 20 \times 10^{-6}\).
05

Present the Result

Thus, the power expended is \(2.0 \times 10^{-5} \text{ J/s}\), which corresponds to option (b) \(2 \times 10^{-ar{j}} \text{ J/s}\).

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Key Concepts

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

Torque Calculation
Torque is a central concept in rotational dynamics. It measures how effectively a force can rotate an object about an axis. Think of it as the rotational equivalent of linear force. To understand torque, imagine opening a door. The force applied at the door's handle creates torque about the hinges. The farther the handle is from the hinge, the greater the torque for the same applied force. This relationship is mathematically expressed as:\[ \text{Torque} (\tau) = \text{Force} \times \text{Lever Arm} \]In the exercise provided, torque is given directly as a value \(\left(\frac{5}{\pi}\right) \times 10^{-6} \text{ Nm}\). This means there is a force acting on a specific point on a rotating body, causing it to spin.Understanding the concept of torque will help you conceptualize problems involving rotational motion and understand how forces affect rotational systems.
Angular Velocity
Angular velocity describes how quickly an object rotates around a point or axis. It is akin to linear velocity but in a rotational context. The standard unit for angular velocity is radians per second \(\text{rad/s}\). To convert revolutions per second into radians per second, recall that one full circle is \(2\pi\) radians.For example, if a body completes 2 revolutions in one second, its angular velocity would be:\[ \text{Angular Velocity} (\omega) = 2 \times 2\pi = 4\pi \text{ rad/s} \]This calculation is vital for understanding how fast something is rotating. In our problem, knowing the angular velocity allows us to calculate the rotational power applied to the body as it spins.
Revolutions per Second
Revolutions per second is a measure of rotational speed. It tells us how many complete turns a rotating object makes each second. This measurement is often used in contexts like motors, gears, and turbines to express how fast these systems operate. By itself, revolutions per second is intuitive - more revolutions mean faster rotation.In scientific and engineering contexts, it’s crucial to translate revolutions into radians to work with other rotational formulas. As noted earlier, 1 revolution equals \(2\pi\) radians. Therefore:- 2 revolutions per second equals \(4\pi\) radians per second.Converting revolutions to radians is necessary for further calculations, such as finding angular velocity and, subsequently, computing rotational power in our problem.

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