A block of mass M is kept in elevator (lift) which starts moving upward with constant acceleration b as shown in figure. Initially elevator at rest. The block is observed by two observers A and B for a time interval `t=0` to `t=T`. Observer B is at rest with respect to elevator and observer A is standing on the ground.
Q. The observer A finds that the work done by gravity on the block is

Explanation

If lift moves up with acceleration .a.

T=m(g+a)
`=1000[10 + 1]= 11000N`