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Ch 09: Rotation of Rigid Bodies
Young & Freedman Calc - University Physics 14th Edition
Young & Freedman Calc14th EditionUniversity PhysicsISBN: 9780321973610당신이 사용하는 게 아니라요?교과서 변경
9장, 문제 8a

A wheel is rotating about an axis that is in the z-direction. The angular velocity ωz is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 7.00 s. We have taken counterclockwise rotation to be positive. Is the angular acceleration during this time interval positive or negative?

검증된 단계별 안내
1
Determine the formula for angular acceleration (α). Angular acceleration is defined as the rate of change of angular velocity (ω) with respect to time (t). The formula is: α = ωf - ωit, where ωf is the final angular velocity, ωi is the initial angular velocity, and t is the time interval.
Substitute the given values into the formula. The initial angular velocity is ωi = -6.00 rad/s, the final angular velocity is ωf = +4.00 rad/s, and the time interval is t = 7.00 s.
Calculate the numerator of the formula, which is the change in angular velocity: ωf - ωi = 4.00 - (-6.00). Simplify this expression to find the total change in angular velocity.
Divide the change in angular velocity by the time interval to find the angular acceleration: α = 10.007.00. This will give the angular acceleration in rad/s².
Interpret the sign of the angular acceleration. Since the angular velocity is increasing from a negative value to a positive value, the angular acceleration is positive. This indicates that the wheel is speeding up in the counterclockwise direction.

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주요 개념

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

Angular Velocity

Angular velocity is a vector quantity that represents the rate of rotation of an object around an axis. It is measured in radians per second (rad/s) and indicates both the speed and direction of the rotation. In this question, the angular velocity changes from -6.00 rad/s to +4.00 rad/s, indicating a change in the direction of rotation over time.
추천 영상:
가이드 코스
06:18
Intro to Angular Momentum

Angular Acceleration

Angular acceleration is the rate of change of angular velocity over time, typically measured in radians per second squared (rad/s²). It can be positive or negative, depending on whether the angular velocity is increasing or decreasing. In this scenario, the angular acceleration can be determined by analyzing the change in angular velocity from -6.00 rad/s to +4.00 rad/s over the time interval of 7 seconds.
추천 영상:
가이드 코스
12:12
Conservation of Angular Momentum

Direction of Rotation

The direction of rotation is crucial in determining the sign of angular velocity and angular acceleration. In this problem, counterclockwise rotation is defined as positive, while clockwise rotation is negative. The change in angular velocity from a negative to a positive value indicates a transition from clockwise to counterclockwise rotation, which implies that the angular acceleration must be positive during the time interval considered.
추천 영상:
가이드 코스
14:03
Rotational Position & Displacement
관련 실천
교과서 질문

A wheel is rotating about an axis that is in the z-direction. The angular velocity ωz is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 7.00 s. We have taken counterclockwise rotation to be positive. What is the angular displacement of the wheel at t = 7.00 s?

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교과서 질문

The angle θ through which a disk drive turns is given by θ(t) = a + bt - ct3, where a, b, and c are constants, t is in seconds, and θ is in radians. When t = 0, θ = π/4 rad and the angular velocity is 2.00 rad/s. When t = 1.50 s, the angular acceleration is 1.25 rad/s2. What are θ and the angular velocity when the angular acceleration is 3.50 rad/s2?

2103
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교과서 질문

A bicycle wheel has an initial angular velocity of 1.50 rad/s. (a) If its angular acceleration is constant and equal to 0.200 rad/s2, what is its angular velocity at t = 2.50 s? (b) Through what angle has the wheel turned between t = 0 and t = 2.50 s?

1564
views
교과서 질문

A wheel is rotating about an axis that is in the z-direction. The angular velocity ωz is -6.00 rad/s at t = 0, increases linearly with time, and is +4.00 rad/s at t = 7.00 s. We have taken counterclockwise rotation to be positive. During what time interval is the speed of the wheel increasing? Decreasing?

1818
views
교과서 질문

The angle θ through which a disk drive turns is given by θ(t) = a + bt - ct3, where a, b, and c are constants, t is in seconds, and θ is in radians. When t = 0, θ = π/4 rad and the angular velocity is 2.00 rad/s. When t = 1.50 s, the angular acceleration is 1.25 rad/s2. (b) What is the angular acceleration when θ = π/4 rad?

2865
views
교과서 질문

The angle θ through which a disk drive turns is given by θ(t) = a + bt - ct3, where a, b, and c are constants, t is in seconds, and θ is in radians. When t = 0, θ = π/4 rad and the angular velocity is 2.00 rad/s. When t = 1.50 s, the angular acceleration is 1.25 rad/s2. Find a, b, and c, including their units.

1733
views