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A centrifuge in a medical laboratory rotates at an angular speed of \(3600 \mathrm{rev} / \mathrm{min}\). When switched off, it rotates through \(50.0\) revolutions before coming to rest. Find the constant angular acceleration (in \(\mathrm{rad} / \mathrm{s}^{2}\) ) of the centrifuge.

Short Answer

Expert verified
To find the constant angular acceleration of the centrifuge, you need to convert the given values to the correct units, and then substitute into the formula of angular kinematics. Solve the formula for angular acceleration \(\alpha\).

Step by step solution

01

Convert Angular Speed

Firstly, convert the given angular speed from revolutions/minute to radians/second. 1 revolution is equal to \(2\pi\) radians, and 1 minute is equal to 60 seconds. So, \( \omega_0 = 3600 \text{ rev/min} \times \frac{2\pi \text{ rad}}{ \text{rev}} \times \frac{1 \text{ min}}{60 \text{ sec}} \).
02

Convert Angular Displacement

The given angular displacement is in revolutions. Convert it to radians. Therefore, \( \theta = 50.0 \text{ rev} \times \frac{2\pi \text{ rad}}{ \text{rev}}\).
03

Substitute into the Formula and Solve for Angular Acceleration

Substitute \( \omega, \omega_0, \theta\) into the formula \( \omega^2 = \omega_0^2 + 2\alpha\theta\), and solve it for \(\alpha\). Finally, calculate the value of \( \alpha\).

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Key Concepts

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

Centrifuge Angular Speed
Understanding the concept of centrifuge angular speed is essential when dealing with rotational motion. A centrifuge, like the one described in the exercise, rotates at a certain speed, expressed in revolutions per minute (rpm). This speed is a measure of how many complete turns the centrifuge makes in one minute.

To contextualize this with an example, consider a centrifuge that spins at a high speed, say 3600 rpm. This means that in one minute, it makes 3600 complete 360-degree rotations. However, in physics, it is often more useful to express this rotational speed in radians per second (\radians / \radians^2), as radians provide a standard, unit-independent measure of angular displacement. This is where the need for conversion arises, and it is a crucial step to be able to proceed with calculations involving angular acceleration or any other aspect of rotational motion.

In the problem provided, the initial angular speed of the centrifuge is converted from revolutions per minute to radians per second by utilizing the conversion factors that 1 revolution is equivalent to \(2\pi\) radians and 1 minute equals 60 seconds. The formula used is \( \omega_0 = 3600 \times \frac{2\pi}{1} \times \frac{1}{60} \), simplifying the units appropriately to yield the angular speed in radians per second.
Angular Displacement
Angular displacement is the angle through which an object moves on a circular path. It is represented in radians, degrees, or revolutions, depending on the context. One revolution around a circle corresponds to an angle of 360 degrees or \(2\pi\) radians. When we talk about a centrifuge rotating through 50.0 revolutions before stopping, it is important to convert this angular displacement into radians to work with the angular acceleration formula.

Imagine you're watching a spinning centrifuge come to a stop. As it slows down, it covers a certain angular distance before coming to rest. This distance, or angular displacement, is what we can observe visually as the number of times the centrifuge turns. To translate this into a more calculus-friendly measure, we multiply the number of revolutions by \(2\pi\) to find the angular displacement in radians: \( \theta = 50.0 \times 2\pi \).

This conversion is important because it standardizes the measure of rotation and enables us to use the universally applicable equations of motion for rotational systems. Expressing angular displacement in radians is very beneficial when it comes to advanced calculations and theoretical understanding of rotational dynamics.
Radians and Revolutions Conversion
In rotational dynamics, the conversion between radians and revolutions becomes a key step in solving problems. As mentioned earlier, 1 revolution is equivalent to an angle of \(2\pi\) radians. This relation allows for a straightforward conversion process that is vital for calculations involving angular velocity, acceleration, and displacement.

To visualize this concept, imagine you have a circle and you walk along the edge until you've made a complete turn. That's one revolution. If instead we talk in radians, that one complete turn around the circle is the same as traveling an angular distance of \(2\pi\) radians. When dealing with exercises such as calculating angular acceleration, understanding and applying this conversion is important. It requires careful attention to units and knowing that while radians and revolutions represent the same physical concept of rotation, they do so in different mathematical terms.

To convert revolutions to radians, multiply the number of revolutions by \(2\pi\). Conversely, to convert radians to revolutions, divide the number of radians by \(2\pi\). Through this simple arithmetic, complex rotational phenomena are made accessible and solvable.

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Most popular questions from this chapter

A \(40.0\)-kg child takes a ride on a Ferris wheel that rotates four times each minute and has a diameter of \(18.0 \mathrm{~m}\). (a) What is the centripetal acceleration of the child? (b) What force (magnitude and direction) does the seat exert on the child at the lowest point of the ride? (c) What force does the seat exert on the child at the highest point of the ride? (d) What force does the seat exert on the child when the child is halfway between the top and bottom?

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