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Ok dudes, I'm kinda stuck with this here problem, and I'd be very grateful if anyone can help me out a bit:

A drive motor of a cd player is controlled to rotate at a speed of 200 rpm (rotations per minute) when reading a track that's 5.7 cm from the center of the cd.
The speed of the motor must vary in order to read the data at a constant rate.

a) Find the angular speed (in radians per minute) of the drive motor when it is reading a track that's 5.7 cm from the center of the cd.

b) Find the linear speed in cm/sec. of a point on the cd that is 5.7 cm from the center.

I've used:
angular speed = 2pi * w (w = the speed, which is 200 rpm)
and linear speed = angular sp. * radius (which is 5.7),

and I found that the angular speed = 1256 radians/min., and the linear speed = 119.21 cm/sec.

I'm asking, is this correct ?

*brain explodes*

*notices KMC isn't a homework forum*

from what i remember of angular and linear velocity it looks right not 100% though

I have no one else to ask, ok cry?

Originally posted by LanceWindu
*notices KMC isn't a homework forum*

*also notices*

*steals bread*

Originally posted by s|m
Ok dudes, I'm kinda stuck with this here problem, and I'd be very grateful if anyone can help me out a bit:

A drive motor of a cd player is controlled to rotate at a speed of 200 rpm (rotations per minute) when reading a track that's 5.7 cm from the center of the cd.
The speed of the motor must vary in order to read the data at a constant rate.

a) Find the angular speed (in radians per minute) of the drive motor when it is reading a track that's 5.7 cm from the center of the cd.

b) Find the linear speed in cm/sec. of a point on the cd that is 5.7 cm from the center.

I've used:
angular speed = 2pi * w (w = the speed, which is 200 rpm)
and linear speed = angular sp. * radius (which is 5.7),

and I found that the angular speed = 1256 radians/min., and the linear speed = 119.21 cm/sec.

I'm asking, is this correct ?
I think it's ok..

Originally posted by s|m
Ok dudes, I'm kinda stuck with this here problem, and I'd be very grateful if anyone can help me out a bit:

A drive motor of a cd player is controlled to rotate at a speed of 200 rpm (rotations per minute) when reading a track that's 5.7 cm from the center of the cd.
The speed of the motor must vary in order to read the data at a constant rate.

a) Find the angular speed (in radians per minute) of the drive motor when it is reading a track that's 5.7 cm from the center of the cd.

b) Find the linear speed in cm/sec. of a point on the cd that is 5.7 cm from the center.

I've used:
angular speed = 2pi * w (w = the speed, which is 200 rpm)
and linear speed = angular sp. * radius (which is 5.7),

and I found that the angular speed = 1256 radians/min., and the linear speed = 119.21 cm/sec.

I'm asking, is this correct ?

In all do Honesty...I would love to help you...but I don't understand all that technical stuff...sorry.

Allrighty then
Thanks.

Just noticed this post and came here off of Google! Unfortunately, the answers are incorrect. I know this because I just did a similar problem such as this one and I figured I'd go on here and complete the problem. Here's the answer to your question (I know I'm years late, but here it is anyways!)

a. Find the angular speed of the wheel.
So to get the angular speed of the wheel, you need to take the number of revolutions per minute and multiply it by the angle (in radians) it turns per minute. This will give us the radians per minute, which is the 'angular speed' that we are looking for. In this equation, π = pi (3.14159...)

angular speed = (200 revolutions / 1 minute) * ( radians / 1 revolution)
angular speed = 400π radians per minute.

Note that doing this will cancel out the 'revolution' units and you will be left with minutes and radians - which is the units we need for angular speed.

b. Find the linear speed in cm/sec of a point on the cd that is 5.7 cm from the center.
Here to get the linear speed of the wheel, you need to use this formula (where s/t is linear speed, θ/t is angular speed, and r is the radius.) The equation looks like this:

s / t = r * (θ/t)

From here you just find the angular speed plugging in the values given to you in the problem. r = 5.7 cm; (θ/t) = 400 radians/min; (s / t) = what we need to find.

Hence...

s / t = 5.7 cm * (400π radians / 1 minute) = 2280π centimeters per minute

However, we aren't finished yet. Notice the problem asks for the units in centimeters per second! So here we need to do unit conversions to cancel out minutes and replace them with seconds. We do it like this:

linear speed = (2280π centimeters / 1 minute) * (1 minute / 60 seconds) = 38π centimeters per second
Making 38π cm/sec your linear speed!

I know nobody asked me to do this problem, but I hope I helped! I checked with my professor and some other students, and it looks like this is the right answer. Happy solving!

Wow...Better late than never I guess

Lol

Originally posted by MathNewbie
Just noticed this post and came here off of Google! Unfortunately, the answers are incorrect. I know this because I just did a similar problem such as this one and I figured I'd go on here and complete the problem. Here's the answer to your question (I know I'm years late, but here it is anyways!)

a. Find the angular speed of the wheel.
So to get the angular speed of the wheel, you need to take the number of revolutions per minute and multiply it by the angle (in radians) it turns per minute. This will give us the radians per minute, which is the 'angular speed' that we are looking for. In this equation, π = pi (3.14159...)

angular speed = (200 revolutions / 1 minute) * ( radians / 1 revolution)
angular speed = 400π radians per minute.

Note that doing this will cancel out the 'revolution' units and you will be left with minutes and radians - which is the units we need for angular speed.

b. Find the linear speed in cm/sec of a point on the cd that is 5.7 cm from the center.
Here to get the linear speed of the wheel, you need to use this formula (where s/t is linear speed, θ/t is angular speed, and r is the radius.) The equation looks like this:

s / t = r * (θ/t)

From here you just find the angular speed plugging in the values given to you in the problem. r = 5.7 cm; (θ/t) = 400 radians/min; (s / t) = what we need to find.

Hence...

s / t = 5.7 cm * (400π radians / 1 minute) = 2280π centimeters per minute

However, we aren't finished yet. Notice the problem asks for the units in centimeters per second! So here we need to do unit conversions to cancel out minutes and replace them with seconds. We do it like this:

linear speed = (2280π centimeters / 1 minute) * (1 minute / 60 seconds) = 38π centimeters per second
Making 38π cm/sec your linear speed!

I know nobody asked me to do this problem, but I hope I helped! I checked with my professor and some other students, and it looks like this is the right answer. Happy solving!

https://media.giphy.com/media/oaPcDncoLfgjK/giphy.gif

hey mr wilson. remember that math question i got wrong in grade 6? heres the answer. i dont care if its been twelve years. eat my dick old man.

Oh no, Bloigen was banned.

No one on KMC will genuinely care about a math problem on this level. Nice try, troll. I truly wish people on this board would take things more seriously.

I always liked the method of "If all else fails KICK ITS ASS!"

https://media.giphy.com/media/E7TjVOF3MoRFu/giphy.gif

A good kick up the ass can solve most probs.