A body is kept in the pan of a spring balance kept in an elevator. The reading of the spring scale will be maximum when the elevator

Options

A. is at rest
B. moves down with an acceleration a
C. moves upwards with an acceleration a
D. cable breaks and the elevator falls freely under gravity

Answer

C

Explanation

The scale reading is
(i) mg : at rest
(ii) `m(g-a)` : downward acceleration
(iii) `m(g+a)` : upward acceleration
(iv) `m(g-g)=0` for free fall
Thus when it is accelerated upwards the scale reading is maximum.