If two current phasors, having magnitude 12A and 5A intersect at an angle of 90 degrees, calculate the resultant current.
a) 13 A
b) 10 A
c) 6 A
d) 5 A

Answer

A

Explanation

i. given Mass of man = 60 kg
Let R'= Apparent weight of man in this case
From free body diagram of man,
`R'+T-60g=0`
`rarr T= 60g=R'` …………..i. `
From free body diagram of box,
`T-R'-30g=0` ……..ii.
From equation i.
` 60g-R'-R-30g=0`
`R'=15g`
)
Hence weight shown by the machine is 15 kg.
ii. To get his correct wight, suppose the applied force is T and so, accelerates upward with a in this case
Given that correct weight = R= 60g where g= acceleratioin due to gravity Form the free body diagram of the man
` T'+R-60g-60a=0`
`T'-60a=0` [since R=60g]
`rarr T'=60a` ...i.
From the free body diagram of the box,
`T'-R-30g-30a=0`
`rarr T' -60g-30g-30a=0`
rarr T'-30a+90g=0`
`rarr T'=30a-900`.......ii.
From equation i. and ii we get
`T'=2T'-1800`
`rarr T'=1800N` So he should exert 1800 N force on the rope to get correct reading.