Effort = $p = \frac{S_2 – S_1}{2}$

Power $= p \times h$

Numerical:

$h = \frac{y}{x} (r_2 – r_1)$

$60 = \frac{100}{150} (r_2 – 80)$

$r_2 = 170 \ mm$

$N_1 = 300\ rpm$ $\rightarrow$ $r_1 = 80\ mm$

$N_2 = ?$ $\rightarrow$ $r_2 = 170\ mm$

$\rightarrow$ $S = …