# Rotational Velocity Homework: Find Accel & Distance for Stopping Wheel

• samprots
In summary, the conversation discusses a wheel with a rotational velocity of 14 rad/s clockwise, and the friction between a hand and the rim stopping it. The question asks for the rotational acceleration and the distance the wheel rotates while slowing to a stop. The attempted solution incorrectly uses an equation and does not consider proper units. The expert suggests going back to the textbook and carefully reviewing the equation and units.
samprots

## Homework Statement

A wheel has a rotational velocity of 14 rad/s clockwise you place your hand against the wheel and the friction between your hand and the rim stops it
a) If it takes 5s to stop the wheel what is its rotational acceleration
b)How far does the wheel rotate while slowing to a stop?

## The Attempt at a Solution

I got A very easy just taking 14/5 but am struggling with part B
Here is what I have so far, and I know its wrong but cannot figure it out
any help would be greatly appreciated

W.t+1/2t(squared)

I have 14*5+1/2*2.8(squared)
70+3.92=73.92

Any help would be greatly appreciated again thanks

Bump, any clarification that can be done on my part?

Wow thanks for the help, your all so great!

W.t+1/2t(squared)
Is this supposed to be an equation? Write the whole thing out. Anyway, this equation isn't even correct. You left out a variable. Go back to your textbook and look it up again.

I have 14*5+1/2*2.8(squared)

Even if this was the right equation, you've messed up the calculation. t is not "2.8". Did you try to see if your units worked out properly? If they don't, then that's an indication you are doing something wrong.

Instead of bumping your thread every 20 minutes, try spending the time working on figuring out what's wrong yourself. A careful look at the textbook should have at least made you notice something was wrong with your equation.

Was that helpful enough for you?

## 1. What is rotational velocity and how is it calculated?

Rotational velocity is a measure of how fast an object is rotating around a fixed axis. It is calculated by dividing the angular displacement (in radians) by the time taken for that rotation.

## 2. What is the equation for finding acceleration using rotational velocity?

The equation for finding acceleration using rotational velocity is a = ω^2 * r, where ω is the rotational velocity in radians per second and r is the radius of the rotating object.

## 3. How can I determine the distance traveled by a stopping wheel using rotational velocity?

To determine the distance traveled by a stopping wheel, you need to know the initial rotational velocity, final rotational velocity, and the time taken to stop. You can use the equation d = (ω_i + ω_f)/2 * t, where ω_i is the initial rotational velocity, ω_f is the final rotational velocity, and t is the time taken.

## 4. What factors can affect the rotational velocity of a wheel?

The rotational velocity of a wheel can be affected by the radius of the wheel, the mass of the wheel, and the applied torque. Friction and air resistance can also have an impact on the rotational velocity.

## 5. How does rotational velocity relate to linear velocity?

Rotational velocity and linear velocity are related through the equation v = ω * r, where v is the linear velocity, ω is the rotational velocity, and r is the radius of the rotating object. This means that as the rotational velocity increases, the linear velocity also increases.

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