Converting Chord Length to Radians: A Confusing Concept?

[Isquarey]

Homework Statement

Coverting Cord length to radians and the other problem is: A ball Radius = 12 CM, rolls 15 M, across the gym floor. Through what angle does the ball rotate?
We just started this today and I am very confused by it. the other question is converting 11.6 CM Chord Length into Radians.

Homework Equations

O=s/r

The Attempt at a Solution

I don't know how to convert chord length to radians and on the next one I converted 15M to centimeters and then i plugged it into the formula doing 1500CM/12CM which gets me 125 Radians and then I did 125(180/3.14) and got 7165 Degrees which cannot be correct.

 

[NascentOxygen]

If it makes many rotations, then angle of rotation will exceed 360°.

 

[lightgrav]

cord length, as if a cord is wrapped around the circumference?
or chord length, as a straight line from one circumference point to another?
(Your small ball does rotate 125 radians to roll 15 meters.)

 

[Isquarey]

A cord as in straight line across it

 

[Isquarey]

cord length, as if a cord is wrapped around the circumference?
or chord length, as a straight line from one circumference point to another?
(Your small ball does rotate 125 radians to roll 15 meters.)

Cord length as in a straigt line across it

 

[lightgrav]

did you draw it? I suggest also draw 2 radial lines from the center to those circumference points . . . maybe one in the center of the chord, also.

 

[Isquarey]

did you draw it? I suggest also draw 2 radial lines from the center to those circumference points . . . maybe one in the center of the chord, also.

I did draw it and i have a problem worked out to get the cord i just can't figure out how to work back words from it I know have to cord is 5.8 CM and there is a 90 Degree angle there am i supposed to do -TAN(Y/X) ?

 

[lightgrav]

YES! we love right triangles! (don't forget the other half chord)

 

[Isquarey]

alright cool thanks