How is the equation given for v_b tangent to it?

[kostantina]

Homework Statement

I'm trying to follow a solved example in the book. I understand everything except one "trivial" (for most of you) analysis of the tangent velocity vector v_b. Because v_b is unknown it is written as its magnitude times the direction it follows constrained in a circular path.

However, my understanding of v_b written as in the picture followed is not tangent. That is the vector that describes the radius of the path, and not the perpendicular to the radius which will be the instantaneous velocity.

Homework Equations

Please see attached picture

The Attempt at a Solution

how is the equation given for v_b tangent to it? this is the vector describing the radius of the path?

Thank you

 

[NascentOxygen]

That right triangle with sides 1 and 1, on the radius of the circular path, indicates that at the current position B is constrained to moving as much to the right as upwards, per unit of time, meaning a velocity vector having equal horiz and vertical components, at the instant represented.

 

[kostantina]

Thank you, makes sense now. Wish I'd asked earlier.