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zainabrehman
a body of mass 2 kg is suspended in an elevator by means of a spring balance the balance reads its weight when elevator moves up with an acceleration of 5ms_2 as 30.5n b 29.6n c 26.5n d 9.8n
this question is a bit lengthy....
the actual weight of the mass is 20 newtons......first of all..
when the elevator moves upward with an acceleration a = 5 m/s^2 ......then the spring balance will show(give reading) of apparent weight more than the actual weight ..... which means that the choice "d"----9.8 is definitely wrong....
now while the elevator is moving upward with an acceleration ...... there are two forces acting on it ......the upward tension "T" and downward weight "w".....
As the mass "m" along with the elevator are accelerating upward with acceleration "a".....So a net force F=ma is acting in the upward direction ..... this net force F=ma= the difference between T and w. T>W because the elevator+mass are both accelerating upward.
Therefore, F=ma=T-W || ma=T-W Putting values|| ma=T-mg|| T=ma+mg|| T=m(a+g)|| T=2(5+9.8)|| T=29.6N As the tension is equal to the apparent weight of the mass being shown by the spring balance....
So option b is the right choice....
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