Physics and circular motion - finding speed with rpm and radius

The blade on a table saw spins at 3450 rpm. It's radius is 12.5 cm. What is the speed of a tooth on the edge of the blade, in both m/s and mph? Please show how to get these?? Thanks!!

3450rpm = 3450rev/min(2πrad/1.00rev)
(1.00min/60.0s)
= 361rad/s

The diameter of the blade is given, but we need its radius in meters, which is:

r = D/2(1.00m/100cm)
= 25.0cm/2(1.00m/100cm)
=0.125m

The speed of a blade tip in meters per second is:

v = rω
= 0.125m(361rad/s)
= 45.1m/s

In miles per hour:

45.1m/s = 45.1m/s(3.28081ft/1.00m)(1.00mile/5280ft…
(3600s/1.00hour)
= 101mph

Hope this helps

or this way

θ ' = (3450 rev/min) ⁄ (60 sec/rev) = 57.5 rev/sec

R = (25cm) ⁄ 2 = 12.5 cm = 0.125 meters

 C = 2π • R
 C = 2π • (0.125)
 C = (π ⁄ 4) meters/rev

    speed = (π ⁄ 4) • (57.5) = 45.16 m/sec

 Conversion: 2.237 (mi/h) ⁄ (m/sec)

    (2.237) • (45.16) = 101 mi/h