Question

A system consisting of two masses connected by a massless rod lies along the x-axis. A 0.4 kg mass is at a distance x = 2 m while a 0.6 kg mass is at a distance x = 7 m. The x-coordinate of the center of mass is

• A. 5 m
• B. 3.5 m
• C. 4.5 m
• D. 4 m

Answer 1

Answer: (A)

5 m

Answer 2

The x-coordinate of center of mass
$x=\frac{m_1x_1+m_2x_2}{m_1+m_2}$
Here $m_1=0.4 kg ,x_1=2m$
$m_2=0.6 kg ,x_2=7m$
hence $x=\frac{0.4 \times 2 +0.6 +7}{0.4 +0.6}$
$x=\frac{5}{1}=5m$