/*! 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 71 While riding a multispeed bicycl... [FREE SOLUTION] | 91Ó°ÊÓ

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While riding a multispeed bicycle, the rider can select the radius of the rear sprocket that is fixed to the rear axle. The front sprocket of a bicycle has radius 12.0 \(\mathrm{cm} .\) If the angular speed of the front sprocket is 0.600 rev/s, what is the radius of the rear sprocket for which the tangential speed of a point on the rim of the rear wheel will be 5.00 \(\mathrm{m} / \mathrm{s} ?\) The rear wheel has radius 0.330 \(\mathrm{m} .\)

Short Answer

Expert verified
The radius of the rear sprocket is approximately 0.0299 m.

Step by step solution

01

Understand the Problem

We need to find the radius of the rear sprocket given the tangential speed of the rear wheel, the radius of the rear wheel, the radius of the front sprocket, and its angular speed.
02

Calculate the Tangential Speed at the Front Sprocket

We know that the angular speed of the front sprocket is 0.600 rev/s. First, convert this to radians per second using the relation \( 1 \text{ rev} = 2\pi \text{ radians} \):\[ \omega_f = 0.600 \cdot 2\pi \approx 3.77 \text{ rad/s} \]Now, the tangential speed \(v_f\) at the front sprocket is calculated as:\[ v_f = \omega_f \times r_f \]where \( r_f = 0.12 \text{ m (12 cm converted to meters)} \). Thus:\[ v_f = 3.77 \times 0.12 = 0.4524 \text{ m/s} \]
03

Relate the Front and Rear Sprockets

The tangential speeds of the chains at both sprockets must be equal (as they are connected by a chain), hence:\[ v_f = v_r \]where \( v_r \) is the tangential speed at the rear sprocket. Rearrange the relationship using:\[ v_r = \omega_f \cdot r_r \]Now, equate to find \( r_r \):\[ 0.4524 = \omega_r \cdot r_r \]
04

Convert Rear Wheel Speed to Angular Speed

The tangential speed of the rear wheel \( v_t = 5.00 \text{ m/s} \) can be written in terms of its angular velocity \( \omega_{wheel} \) and the radius of the rear wheel \( r_{wheel} = 0.33 \text{ m} \):\[ 5.00 = \omega_{wheel} \cdot 0.33 \]Solving for \( \omega_{wheel} \):\[ \omega_{wheel} = \frac{5.00}{0.33} \approx 15.15 \text{ rad/s} \]
05

Derive Rear Sprocket Radius Using Angular Velocities

The angular velocity is the same from the chain link between sprockets, thus \( \omega_{wheel} = \frac{v_r}{r_{wheel}} \). From Step 3, we have:\[ v_f = \omega_r \cdot r_r = 0.4524 \approx 15.15 \times r_r \]Solve for radius of the rear sprocket \(r_r\): \[ r_r = \frac{0.4524}{15.15} \approx 0.0299 \text{ m} \]
06

Final Calculation Review

Re-check all steps for consistency. Ensure all unit conversions are correct and that the equality of tangential speeds through the chain mechanism is confirmed in the setup.

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Key Concepts

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

Angular Speed
Angular speed refers to how fast an object rotates or revolves relative to another point, typically the center of a circle. It measures the rate of change of angular displacement and is usually expressed in radians per second (rad/s). In the bicycle problem, the angular speed of the front sprocket is given as 0.600 revolutions per second.

To work with this measure in equations, it's often converted to radians per second, given that one full revolution equals \(2\pi\) radians. Hence, the conversion for angular speed is calculated using the relation: \[ \omega_f = \, \text{rev/s} \, \times \, 2\pi \, \text{rad} \] This fundamental concept in mechanics helps us understand rotational motion and is key in calculating related quantities like tangential speed.
Tangential Speed
Tangential speed measures how fast a point on a rotating object's edge is moving in a straight line. It is directly linked to angular speed. For a rotating circle, the tangential speed of a point on the perimeter can be determined with the formula: \[ v = \omega \times r \] where \(v\) is the tangential speed, \(\omega\) is the angular speed, and \(r\) is the radius.

In this bicycle problem, the challenge is to find the tangential speed at the rear sprocket. This speed is equal to the tangential speed of the chain moving between the two sprockets. Ensuring the same tangential speed across different parts of a mechanical system is crucial for smooth operation. Understanding tangential speed will enhance your grasp of linear motion in a rotational framework.
Sprocket Radius
The sprocket radius is the distance from the center of the sprocket to its edge. In bicycles, sprocket radius affects gear ratios, which influence speed and efficiency. In this exercise, we need to calculate the rear sprocket's radius to achieve a specific tangential speed.

Given the front sprocket's radius and angular speed, we used these details to find the equivalent tangential speed of the chain shared with the rear sprocket. This requires the calculation: \[ v = \omega \times r \] to find the necessary rear sprocket radius that corresponds with the desired system speed.
A correct calculation of sprocket radii helps determine the bike's performance on different terrains and speeds.
Mechanical Systems
A bicycle is a classic example of a mechanical system, where components like the chain, sprockets, and wheels collaborate to transfer human energy into motion. In this scenario, the interaction between the front and rear sprocket through a chain acts as the central system for movement.

The concept that the tangential speed of the chain must remain constant throughout is a principle often seen in such systems. It is key to ensuring synchronized movements among parts. Recognizing these interactions helps comprehend how mechanical systems operate efficiently, achieving desirable outcomes like the specific speed.
Unit Conversion
Unit conversion is vital in physics, ensuring that all measurements are in compatible units for calculations. In mechanical problems like this bicycle example, you convert angular speeds from revolutions per second to radians per second and convert lengths from centimeters to meters.

This ensures accuracy as unit conversion aligns all parts of your calculation under a common measurement system. For example, converting cm to m simplifies calculating tangential speed: \[ 1 \, \text{cm} = 0.01 \, \text{m} \] Accurate unit conversions ensure all calculations are coherent, leading to reliable solutions.

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