Question

A body of mass 2 kg is hung on a spring balance mounted vertically in a lift. If the lift descends with an acceleration equal to the acceleration due to gravity ‘g’, the reading on the spring balance will be

Answer 1

Mass of the body  m=2kg
Acceleration of lift in downward direction a=g
Let the reading of spring balance be N.
Equation of motion for the body :   ma=mg−N
Or  mg=mg−N      (∵a=g)
⟹  N=mg−mg=0
Thus the spring balance will show zero reading.