A fan blade rotates with angular velocity given by ωz(t) = g - bt2, where g = 5.00 rad/s and b = 0.800 rad/s3. Calculate the angular acceleration as a function of time.
Ch 09: Rotation of Rigid Bodies
9장, 문제 3b
The angular velocity of a flywheel obeys the equation ωz(t) = A + Bt2, where t is in seconds and A and B are constants having numerical values 2.75 (for A) and 1.50 (for B). What is the angular acceleration of the wheel at (i) t = 0 and (ii) t = 5.00 s?
검증된 단계별 안내1
Understand the problem: The angular velocity of the flywheel is given as a function of time, \( \omega_z(t) = A + B t^2 \), where \( A = 2.75 \) and \( B = 1.50 \). Angular acceleration is the time derivative of angular velocity, \( \alpha(t) = \frac{d\omega_z(t)}{dt} \). We need to calculate \( \alpha(t) \) at \( t = 0 \) and \( t = 5.00 \ \text{s} \).
Differentiate the angular velocity equation with respect to time to find the angular acceleration: \( \alpha(t) = \frac{d}{dt}(A + B t^2) \). Since \( A \) is a constant, its derivative is zero, and the derivative of \( B t^2 \) is \( 2 B t \). Thus, \( \alpha(t) = 2 B t \).
Substitute the value of \( B = 1.50 \) into the angular acceleration equation: \( \alpha(t) = 2 (1.50) t = 3.00 t \). This is the expression for angular acceleration as a function of time.
To find the angular acceleration at \( t = 0 \), substitute \( t = 0 \) into \( \alpha(t) = 3.00 t \): \( \alpha(0) = 3.00 (0) \). Simplify to find the angular acceleration at \( t = 0 \).
To find the angular acceleration at \( t = 5.00 \ \text{s} \), substitute \( t = 5.00 \) into \( \alpha(t) = 3.00 t \): \( \alpha(5.00) = 3.00 (5.00) \). Simplify to find the angular acceleration at \( t = 5.00 \ \text{s} \).

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이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.
영상 길이:
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주요 개념
질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.
Angular Velocity
Angular velocity is a measure of how quickly an object rotates around an axis, typically expressed in radians per second. In the given equation, ω_z(t) = A + Bt², the angular velocity depends on time and is influenced by constants A and B. Understanding this concept is crucial for analyzing rotational motion and determining how the speed of rotation changes over time.
추천 영상:
Intro to Angular Momentum
Angular Acceleration
Angular acceleration refers to the rate of change of angular velocity over time, usually expressed in radians per second squared. It can be calculated as the derivative of angular velocity with respect to time. In this case, to find the angular acceleration, we differentiate the given equation for angular velocity, which will provide insights into how the rotation speed of the flywheel changes at specific moments.
추천 영상:
Conservation of Angular Momentum
Differentiation in Physics
Differentiation is a fundamental mathematical process used in physics to determine rates of change. In the context of the problem, differentiating the angular velocity function with respect to time allows us to find the angular acceleration. This concept is essential for analyzing dynamic systems, as it helps relate position, velocity, and acceleration in both linear and rotational motion.
추천 영상:
Gravitational Force from a Solid Disk
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교과서 질문
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교과서 질문
A fan blade rotates with angular velocity given by ωz(t) = g - bt2, where g = 5.00 rad/s and b = 0.800 rad/s3. Calculate the instantaneous angular acceleration αz at t = 3.00 s and the average angular acceleration αav-z for the time interval t = 0 to t = 3.00 s. How do these two quantities compare? If they are different, why?
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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. Find a, b, and c, including their units.
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