Physics I need help

Question

The blade of a saw is travelling in circular motion for 12 revolutions in 0.1s with a radius of 0.3m.

1) How much is the frequency in RPM 2) How much is the speed of the blade at the outer edge?

Answer 1

Number of revolutions ,N = 12 rev

Time, t = 0.1 s

           =(0.1/60) min

Radius of the blade, r  = 0.3 m

1)

Calculate the frequency in RPM by using the formula.

f = N/t

 = 12/(0.1/60)

  = (12)(60)/(0.1)

  = 720/0.1

  = 7200 RPM

Therefore, the frequency in RPM is 7200 RPM.

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2)

Calculate the angular velocity in rad /s.

ω = 2πf/60

   =2π(7200)/60

   = 753.6 rad/s

Calculate the speed of the blade by using the formula.

v =rω

  = (0.3)(753.6)

  =226.08 m/s

Therefore, the speed of the blade is 226.08 m/s