Calculate the magnitude of angular acceleration

In summary, a record player with a normal rotation rate of 18 rev/m takes 70 seconds to slow down to a stop when turned off. The magnitude of its angular acceleration can be calculated using kinematic equations for angular motion. If this were a linear motion problem, the deceleration could be calculated under constant deceleration. This is a homework problem and suggestions rather than answers are given due to forum rules.
  • #1
reformedman
2
0

Homework Statement


A record player rotates normally at a rate of 18 rev/m.
It takes 70 seconds for it to slow down to a stop when you turn it off.

Homework Equations


Calculate the magnitude of its angular acceleration.

The Attempt at a Solution


answer key says the correct answer should be .027 rad/s^2
 
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  • #2
Hi reformedman, Welcome to Physics Forums.

You've stated what needs to be found in the Relevant equations section of the template. That's not a relevant equation, it's part of the problem statement. So what equations do you know that might apply to this type of problem?

What have you tried?
 
  • #3
You need to make an attempt to solve the problem before we can help. What do you know about angular velocity and angular acceleration?
 
  • #4
it's been 30 years since college and I was just browsing the net when I found that familiar problem. I seem to recall something about 2 pi related to rads somehow. I'm not really pressed for the solution, was just wondering. Glad I found this forum though, looking around a bit.
 
  • #5
reformedman said:
it's been 30 years since college and I was just browsing the net when I found that familiar problem. I seem to recall something about 2 pi related to rads somehow. I'm not really pressed for the solution, was just wondering. Glad I found this forum though, looking around a bit.
Well, if you want to solve the problem it looks like you'll need to review the basics. There are plenty of resources on the web if you search the appropriate terms. You'll be looking for kinematic equations related to angular motion (or rotational kinematics). They're of the same form as those for linear motion (look up: SUVAT), but use angular quantities rather than linear ones.
 
  • #6
reformedman said:
it's been 30 years since college and I was just browsing the net when I found that familiar problem. I seem to recall something about 2 pi related to rads somehow. I'm not really pressed for the solution, was just wondering. Glad I found this forum though, looking around a bit.

Don't over think this one. If this were linear motion and I gave you a starting speed and said it took 70 seconds to stop under constant deceleration would you know how to calculate the deceleration?

Also, the reason you are getting cagey suggestions instead of answers is because this is a "homework" forum. There are also non- homework forums. However this looks like a homework problem so you would probably have to swear vehemently that this isn't homework in order to get a straight answer.
 

What is angular acceleration?

Angular acceleration is the rate at which an object's angular velocity changes over time. It is a measure of how quickly an object is rotating or changing direction.

How is angular acceleration calculated?

Angular acceleration is calculated by dividing the change in angular velocity by the change in time. The formula for angular acceleration is: α = (ω2 - ω1) / (t2 - t1), where α is the angular acceleration, ω is the angular velocity, and t is the time.

What are the units of angular acceleration?

The standard unit of angular acceleration is radians per second squared (rad/s^2). However, it can also be expressed in degrees per second squared (deg/s^2) or revolutions per second squared (rev/s^2).

How does angular acceleration relate to linear acceleration?

Angular acceleration and linear acceleration are related by the radius of rotation. The linear acceleration of a point on a rotating object is equal to the product of its angular acceleration and the distance from the axis of rotation. This relationship can be expressed as a = α * r, where a is linear acceleration, α is angular acceleration, and r is the radius of rotation.

What factors can affect the magnitude of angular acceleration?

The magnitude of angular acceleration can be affected by several factors, including the object's mass, shape, and the torque applied to it. A larger mass or shape will require more torque to produce the same angular acceleration as a smaller mass or shape. Additionally, friction and air resistance can also impact the magnitude of angular acceleration.

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