Fig show two bodies A and B of masses 2.5 kg and 2.8 kg respectively from a rigid support by two inextensible wires each of length 1.8 m . The upper wire is of negligible mass and lower wire is of mass `1.5 kg // m` . If the entire system moves upwards with an acceleration of `2 m//s^(2)`, find tension (i) at middle point p of upper wire (ii) at middle point Q of lower wire . Take `g =10 m//s^(2)`
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Explanation

As the system moves upwards with an acceleration ` a = 2 m// s^(2) `
`:.` tension in the wire `T= R = m (g+a)`
(i) For point P at point of upper wire
`m= m_(A) + m_(B)` + mass of lower wire
`= 2.5 + 2.8 + 1.8 xx 1.5 = 8.0 kg`
`:. T = 8 (10+2) = 96 N`
(ii) For point Q mid point of lower wire
`m = m^(B)` + mass of half length of lower wire
`= 2.8 + (1.8)/(2)xx 1.5 = 4.15 kg `
`:. T = m (g+a) = 4.15 (10+2) = 49.8 N` .