Figure shows a uniform rod of length 30 cm having a mass of 3.0 kg. The strings shown in the figure are pulled by constant forces of 20 N and 32N. Find the force exerted by the 20 cm part of the rod on the 10 cm part. All the surfaces are smooth and the strings and the pulleys are light.

Explanation

Given that `a=3.26 m/s^2 `
` T=3.9N`
After 2 sec, mass `m_1 ` hass velocity `
` v=u+at=0+3.26xx2`
` =6.52 m/supward
At this time `m_2` is moving 6.52 m/s downward.

Ast time 2 sec , `m_1` stops for a moment.
But `m_1` is moving upward with velocity 6.52 m/s. It will continue to move til fiN/Al velociyt (at highest point ) becomes zero.
`Her, v=0, u=6.52`
a=-g=-9.8 m/s^2 `
[since `m_1` is movng upward]
`v=u+at=6.52+(-9.8)t`
`rarr t= 6.52/9.8 0.66 = 2/3 sec.`
During this period of `2/3` sec, mass `m_2` also starts moving downward. So the string becomes tight again after time of ` 2/3` sec.