  Dynamic hysteresis, viz., delay in switching of a bistable system on account
of the finite sweep rate of the drive has been extensively studied in dynamical
and thermodynamic systems. Dynamic hysteresis results from slowing of the
response around a saddle-node bifurcation. As a consequence, the hysteresis
area increases with the sweep rate. Mean-field theory, relevant for noise-free
situations, predicts power law scaling with the area scaling exponent of 2/3.
We have experimentally investigated the dynamic hysteresis for a
thermally-driven metal-insulator transition in a high quality NdNiO$_3$ thin
film and found the scaling exponent to be about 1/3, far less than the mean
field value. To understand this, we have numerically studied Langevin dynamics
of the order parameter and found that noise, which can be thought to parallel
finite temperature effects, influences the character of dynamic hysteresis by
systematically lowering the dynamical exponent to as small as 0.2. The power
law scaling character, on the other hand, is unaffected in the range of chosen
parameters. This work rationalizes the ubiquitous power law scaling of the
dynamic hysteresis as well as the wide variation in the scaling exponent
between 0.66 and 0.2 observed in different systems over the last 30 years.
