  Bright-rimmed clouds (BRCs) are excellent laboratories to explore the
radiation-driven implosion mode of star formation because they show evidence of
triggered star formation. In our previous study, BRC 18 has been found to
accelerate away from the direction of the ionizing Hii region because of the
well known "Rocket Effect". Based on the assumption that both BRC 18 and the
candidate young stellar objects (YSOs) are kinematically coupled and using the
latest Gaia EDR3 measurements, we found that the relative proper motions of the
candidate YSOs exhibit a tendency of moving away from the ionizing source.
Using BRC 18 as a prototype, we made our further analysis for 21 more BRCs, a
majority of which showed a similar trend. For most of the BRCs, the median
angle of the relative proper motion of the candidate YSOs is similar to the
angle of on-sky direction from the ionizing source to the central IRAS source
of the BRC. Based on Pearson's and Spearman's correlation coefficients, we
found a strong correlation between these two angles, which is further supported
by the Kolmogorov-Smirnov (K-S) test on them. The strong correlation between
these two angles supports the "Rocket Effect" in the BRCs on the plane-of-sky.
