1.

Two masses 8 kg and 12 kg are connected at the two ends of a light inextensible string that goes over a frictionless pulley. Find the acceleration of the masses and the tension in the string when the masses are released.

Answer»

Solution :Let `m_(1)= 8 kgm_(2)= 12 KG`
Lettensionin stringbe T

Let commonaccelerationof systemisa
Accelerationof `m_(1)`is inupwarddirectionaccelerationof `m_(2)`is indownwarddirectionequationof motionof `m_(1)`
Bytakingadditionof equation(1) and(2) we getcommonaccelerationof SYSTEM
`(m_(2)- m_(1))g= (m_(1) + m_(2))a`
`=((12-8)/( 8+12))xx 10`
`T = m_(1)g + m_(1)((m_(2)-m_(1))/( m_(1)+ m_(2))) g`
`T= ((2m_(1)m_(2))/( m_(1)+m_(2)))g`
Substitutingvalue
`T=(2xx 8 xx 12)/( 8+ 12)xx 10`
`T= (2xx960)/(20)`
`:. T = 96 N`
Letmass ofnucleusis mandinitialvelocityv= 0
initialmomentum`vec(p )_(1)=- mV =0`
Afterdisintergrationit isdividedintotwopartlet mass be `m_(1)`and `m_(2)`and velocitybe `vec( V ) _(1)`and`vec(2)` respectively
By lawof conservationof linearmomentum
`vec(p )_(1)= vec( p)_(f)`
`:.,m_(2)v_(2)= -m_(1) m_(1)`
Negativesighshowsthatvelocityof bothfragmentare inmutuallyoppositedirection


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