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A bicycle wheel has an initial angular velocity of 1.50 \(\mathrm{rad} / \mathrm{s}\) . (a) If its angular acceleration is constant and equal to 0.300 \(\mathrm{rad} / \mathrm{s}^{2}\) , what is its angular velocity at \(t=2.50 \mathrm{s} ?\) (b) Through what angle has the wheel turned between \(t=0\) and \(t=2.50 \mathrm{s} ?\)

Short Answer

Expert verified
Angular velocity at 2.50 s is 2.25 rad/s; the wheel turns through 4.6875 rad.

Step by step solution

01

Understand the Given Information

We are given an initial angular velocity \( \omega_0 = 1.50 \, \text{rad/s} \) and a constant angular acceleration \( \alpha = 0.300 \, \text{rad/s}^2 \). We need to find the angular velocity \( \omega \) at \( t = 2.50 \, \text{s} \) and the angle \( \theta \) through which the wheel has turned.
02

Use the Angular Velocity Formula

The formula to find the angular velocity at a given time \( t \) is:\[ \omega = \omega_0 + \alpha t \]Substitute the given values:\[ \omega = 1.50 + (0.300)(2.50) \]
03

Calculate Angular Velocity

Evaluate the expression to find \( \omega \):\[ \omega = 1.50 + 0.750 = 2.25 \, \text{rad/s} \]Thus, the angular velocity at \( t = 2.50 \text{s} \) is \( 2.25 \, \text{rad/s} \).
04

Use the Angle Formula

To find the angle \( \theta \) through which the wheel has turned, use the formula:\[ \theta = \omega_0 t + \frac{1}{2} \alpha t^2 \]Substitute the given values:\[ \theta = (1.50)(2.50) + \frac{1}{2}(0.300)(2.50)^2 \]
05

Calculate the Angle Turned

Evaluate the expression for \( \theta \):\[ \theta = 3.75 + \frac{1}{2}(0.300)(6.25) \]\[ \theta = 3.75 + 0.9375 = 4.6875 \, \text{rad} \]The wheel has turned through an angle of \( 4.6875 \, \text{rad} \) between \( t = 0 \) and \( t = 2.50 \text{s} \).

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Key Concepts

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

Angular Velocity
Angular velocity is like how fast something spins around. It's the speed of rotation and is usually measured in radians per second (rad/s).
If you think about a clock, the minute hand has an angular velocity because it rotates around the clock face. In our exercise, the bicycle wheel starts with an initial angular velocity of 1.50 rad/s. This means at the beginning of the observation, every second, the wheel covers 1.50 rad in angular motion.
  • Initial angular velocity (\(\omega_0\)) is what you start with.
  • Final angular velocity (\(\omega\)) is influenced by time and acceleration.
To find how fast the wheel is spinning after some time, we can use the formula: \[\omega = \omega_0 + \alpha t\]This tells us that if you start spinning at a certain speed and then speed up, the final speed depends on how long and how much you've been speeding up.
Angular Acceleration
Angular acceleration describes how quickly an object's rotational speed is changing. It's like the pedal pushing to make a bicycle spin faster or slower. Measured in radians per second squared (rad/s²), it tells us how much the angular velocity is changing every second.
In the exercise, the constant angular acceleration is 0.300 rad/s². It suggests that every second, the wheel's speed increases by 0.300 rad/s.
  • Positive angular acceleration means speeding up.
  • Negative angular acceleration (deceleration) means slowing down.
Whenever you have a constant angular acceleration, it allows you to predict the future angular velocity using the relation with time and initial angular velocity.
Rotational Motion
Rotational motion refers to anything spinning, rotating, or pivoting. It's everywhere in our daily life, from the Earth spinning around its axis to fans rotating in your house. Just like how linear motion is about things moving in straight lines, rotational motion is about moving in circles.
In the context of our bicycle wheel, rotational motion is observed when the wheel turns around its axis. This motion is described by terms like angular velocity and angular acceleration, important parameters that tell us about the speed and manner of rotation.
Understanding rotational motion is crucial as it provides insight into the motion of objects around us and bridges into more complex physics studies involving dynamics and torques.
Angle of Rotation
The angle of rotation is the amount that an object has spun through during rotational motion. Measured in radians, it tells you how much of a circle the rotating object has covered.
For the bicycle wheel, finding out through what angle it has turned means figuring out how many radians it has spun in a period of 2.50 seconds.
  • Initial angular velocity contributes to initial spinning.
  • Angular acceleration increases or decreases the spin over time.
The angle can be computed using the formula:\[\theta = \omega_0 t + \frac{1}{2} \alpha t^2\]This means the angle is affected both by starting speed and acceleration over time, showing a clear relationship between linear and rotational movement.

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Most popular questions from this chapter

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