The radius of the magnetic disk in a 3.5-inch diskette is 1.68 inches. Find the linear speed of a point on the circumference of the disk if it is rotating at a speed of 360 revolutions per minute.

The book answer says: 20.16pi / inches but i want to know how exactly they got it.

Question

The radius of the magnetic disk in a 3.5-inch diskette is 1.68 inches. Find the linear speed of a point on the circumference of the disk if it is rotating at a speed of 360 revolutions per minute. 

The book answer says: 20.16pi / inches but i want to know how exactly they got it.

anonymous · Answer

Think formula for circumference.

lindsey11x16 · Answer

Which would be 2pi1.68

anonymous · Answer

Right, and it is doing 360 times that distance every 60 seconds.

lindsey11x16 · Answer

WHOOOA i think i got it 

so you multiply 2*1.68 to get 3.36. Then multiply by it by 360 revolutions and then you divide by 60 seconds and then 20.16!!

anonymous · Answer

Yep, and your units for speed are in inches per second.

lindsey11x16 · Answer

Thank you so much :)

anonymous · Answer

You're welcome.
Make more sense now?

lindsey11x16 · Answer

I wish. I understand how to do that problem but the next one gets trickier :/