## zainabrehman 4 years ago 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

1. mujtabazarrar

this question is a bit lengthy....

2. mujtabazarrar

the actual weight of the mass is 20 newtons......first of all..

3. mujtabazarrar

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....

4. mujtabazarrar

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".....

5. mujtabazarrar

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.

6. mujtabazarrar

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....

7. mujtabazarrar

So option b is the right choice....

8. mujtabazarrar

Did you understand?