Question

1. A 120cm long uniform rod is balanced at point P with a mass of 125g at one of its ends as shown. Find the mass of the rod

Answer 1

$mg\cdot 0.3+F_1\cdot0.15=F_2\cdot0.45$

$mg\cdot 0.3+\frac{M}{1.2}\cdot0.3\cdot g\cdot0.15=\frac{M}{1.2}\cdot0.9\cdot g\cdot0.45$

$0.125\cdot 0.3+\frac{M}{1.2}\cdot0.3\cdot0.15=\frac{M}{1.2}\cdot0.9\cdot0.45\to$

$M=0.125\ (kg)$ . Answer