Three masses are placed on the x-axis : 300 g at origin, 500 g at x = 40 cm and 400 g at x = 70 cm. The distance of the centre of mass from the origin is:

Options

(a) 40 cm
(b) 45 cm
(c) 50 cm
(d) 30 cm

Correct Answer:

40 cm

Explanation:

Xcm = m₁x₁ + m₂x₂ + m₃x₃ / m₁ + m₂ + m₃
Xcm = 300 x (0) + 500 x (40) + 400 x 70 / 1200
Xcm = 500 x 40 + 400 x 70 / 1200
Xcm = 50 + 70 / 3 = 120 / 3 = 40 cm