an object of mass m is being weighed in an elevator that is moving upward with an acceleration a. What is the eesult if the weighing is done using a spring balance and a pan balance?

Answer 1

With a spring balance, there is an additional tension ma upwards, therefore
the registered weight
= mg+ma=m(g+a)

With a pan balance (one pan object, the other weights)
Both sides experience the same acceleration,
so will exert equally m(g+a) on each side.
Hence it will show true mass.