Each propeller on a King Air twin-engine airplane consists of three blades. Each of mass 10 kg and length 125 cm . The blades may be treated approximately as uniform, thin rods. If the propeller is driven by an engine that develops a torque of `25 pi N`m, how long (in sec). will it take to change the propeller's angular speed from 1400 rpm to 1640 rpm ?

Answer

2

Explanation

`F-5 g=(5g)/6`
`((5+m)g-F=(5+m)g//6)/(mg=(10+m)g//6)`
`rArr 5m =10 rArr m =2 kg `