A stroboscope with a maximum flash rate of 6000 flashes per

A stroboscope with a maximum flash rate of 6000 flashes per minute is used to measure the rate of rotation of a shaft rotating at 41,000 rpm. The flash rate of the strobe is set at 6000 flashes per minute and then the flash rate is slowly reduced until the motion of the rotating shaft appears \"stationary.\" What is the first (highest) flash rate that will \"freeze\" the motion of the rotating shaft? Now the flash rate is slowly reduced some more. What is the second (next highest) flash rate that will \"freeze\" the motion of the rotating shaft?

Solution

Stroboscope maximumum flashing rate per minute = 6000        Rotation of shaft = 41000    RPM                          !/8 of rotation Speed = 5125 RPM        1/9 RPM    4555.55    1/10 of RPM = 4100 RPM

Hence the highest flash rate that will freeze the shaft is 5125 flashes / minute

Next highest flash rate that will freeze the shaft is 4100 flshes / minute