1.

In the fig, find the acceleration of mass m_(2)

Answer»

SOLUTION :`l_(1)+2l_(2)=` constant on differentiating
`v_(1)+2v_(2)=0`
Again differentiating
`a_(1)+2a_(2)=0 RARR a_(1)=-2a_(2)`

.-ve. sign indicates that the accelerations are in opposite direction. Suppose acceleration of `m_(2)` is `a_(2)` downward and then acceleration of `m_(1)` will be `a_(1)` UPWARDS.
`T-m_(1)g=m_(1)a_(1)`
`T=m_(1)g+m_(1)a_(1)`
`m_(2)g-2T=m_(2)a_(2)`

`m_(2)g-2(m_(1)g+m_(1)a_(1))=m_(2)a_(2)`
`m_(2)g-2m_(1)g=m_(2)a_(2)+4m_(1)a_(2)(THEREFORE a_(1)=2a_(2))`
.-. sign should not be substituted
`a_(2)=((m_(2)-2m_(1))g)/(4m_(1)+m_(2))MS^(-2)`


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