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Ch. 10 - Rotational Motion
Giancoli Douglas - Physics for Scientists and Engineers 5th edition
Giancoli Douglas5th editionPhysics for Scientists and EngineersISBN: 9780137488179당신이 사용하는 게 아니라요?교과서 변경
10장, 문제 14

How fast (in rpm) must a centrifuge rotate if a particle 8.0 cm from the axis of rotation is to experience an acceleration of 100,000 g’s?

검증된 단계별 안내
1
Understand the problem: We are tasked with finding the rotational speed of a centrifuge in revolutions per minute (rpm) such that a particle located 8.0 cm (0.08 m) from the axis of rotation experiences a centripetal acceleration of 100,000 g's, where g = 9.8 m/s².
Express the centripetal acceleration formula: The centripetal acceleration \( a_c \) is given by \( a_c = r \omega^2 \), where \( r \) is the radius (distance from the axis of rotation) and \( \omega \) is the angular velocity in radians per second.
Rearrange the formula to solve for \( \omega \): \( \omega = \sqrt{\frac{a_c}{r}} \). Substitute \( a_c = 100,000 \times 9.8 \ \text{m/s}^2 \) and \( r = 0.08 \ \text{m} \) into the equation.
Convert \( \omega \) (angular velocity) to revolutions per minute (rpm): First, note that \( \omega \) is in radians per second. To convert to revolutions per second, use \( \text{revolutions per second} = \frac{\omega}{2\pi} \). Then, multiply by 60 to convert to rpm: \( \text{rpm} = \frac{\omega}{2\pi} \times 60 \).
Substitute the calculated \( \omega \) into the rpm formula to find the final rotational speed. Ensure all units are consistent throughout the calculation.

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Centripetal Acceleration

Centripetal acceleration is the acceleration experienced by an object moving in a circular path, directed towards the center of the circle. It is calculated using the formula a = v²/r, where 'a' is the centripetal acceleration, 'v' is the tangential velocity, and 'r' is the radius of the circular path. In this context, understanding how centripetal acceleration relates to the speed of the centrifuge is crucial for solving the problem.
추천 영상:
가이드 코스
06:48
Intro to Centripetal Forces

Gravitational Acceleration

Gravitational acceleration, denoted as 'g', is the acceleration due to Earth's gravity, approximately 9.81 m/s². In this question, the particle experiences an acceleration of 100,000 g's, which means it is subjected to an acceleration of 100,000 times that of gravity. This concept is essential for converting the acceleration into a usable value for calculations involving the centrifuge's speed.
추천 영상:
가이드 코스
07:32
Weight Force & Gravitational Acceleration

Revolutions Per Minute (RPM)

Revolutions per minute (RPM) is a unit of rotational speed that indicates how many complete turns an object makes in one minute. To find the required RPM for the centrifuge, one must relate the tangential velocity to the angular velocity, which is expressed in RPM. Understanding this relationship is key to determining how fast the centrifuge must rotate to achieve the desired acceleration.
추천 영상:
관련 실천
교과서 질문

The axle of a wheel is mounted on supports that rest on a rotating turntable as shown in Fig. 10–52. The wheel has angular velocity ω₁ = 48.0 rad/s about its axle, and the turntable has angular velocity ω₂ = 35.0 rad/s about a vertical axis. (Note arrows showing these motions in the figure.) What are the directions of ω1\(\overrightarrow{\omega_1}\) and ω2\(\overrightarrow{\omega_2}\) at the instant shown?

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교과서 질문

A turntable of radius R₁ is turned by a circular rubber roller of radius R₂ in contact with it at their outer edges. What is the ratio of their angular velocities, ω₁/ω₂?

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교과서 질문

(II) A child rolls a ball on a level floor 3.1 m to another child. If the ball makes 12.0 revolutions, what is its diameter?

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교과서 질문

The axle of a wheel is mounted on supports that rest on a rotating turntable as shown in Fig. 10–52. The wheel has angular velocity ω₁ = 48.0 rad/s about its axle, and the turntable has angular velocity ω₂ = 35.0 rad/s about a vertical axis. (Note arrows showing these motions in the figure? What is the resultant angular velocity of the wheel, as seen by an outside observer, at the instant shown? Give the magnitude and direction.

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교과서 질문

A child rolls a ball on a level floor 3.1 m to another child. If the ball makes 12.0 revolutions, what is its diameter?

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교과서 질문

The platter of the hard drive of a computer rotates at 7200 rpm (rpm = revolutions per minute = rev/min). If a single bit requires 0.50 μm of length along the direction of motion, how many bits per second can the writing head write when it is 3.00 cm from the axis?

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