Question

A gear train shown in figure consist of gears P, Q, R and S. Gear Q and gear R are mounted on the same shaft. All the gears are mounted on parallel shafts and the number of teeth of P, Q, R and S are 24,45,30 and 80 respectively. Gear P is rotating at 400 rpm. The speed (in rpm) of the gear S is

• A. 100 rpm
• B. 120 rpm
• C. 150 rpm
• D. 200 rpm

Answer 1

The correct option is B 120 rpm

$\frac{N_S}{N_P}=\frac{z_P}{z_S}=\frac{24}{80}$

$N_S=\frac{24}{80}\times 400$

$N_S=120rpm$