Question

a disk of a radius 50 cm rotates at a constant rate of 100 rpm. what distance in meters will a point on the outside rim travel during 30 seconds of rotation?​

Answer 1

Each minute, the disk completes 100 revolutions, so a point on the rim traverses a distance of 100 times the circumference of the disk and would have a linear speed of

100 rev/min

= (100 rev/min) × (2π × 50 cm/rev) × (1/100 m/cm) × (1/60 min/s)

= 5π/3 m/s ≈ 5.236 m/s

Then after 30 s of rotation, the point would have traveled a distance of

(5π/3 m/s) × (30 s) = 50π m ≈ 157.08 m