  Understanding of the kinematic evolution of Coronal Mass Ejections (CMEs) in
the heliosphere is important to estimate their arrival time at the Earth. It is
found that kinematics of CMEs can change when they interact or collide with
each other as they propagate in the heliosphere. In this paper, we analyze the
collision and post-interaction characteristics of two Earth-directed CMEs,
launched successively on 2012 November 9 and 10, using white light imaging
observations from STEREO/SECCHI and in situ observations taken from WIND
spacecraft. We tracked two density enhanced features associated with leading
and trailing edge of November 9 CME and one density enhanced feature associated
with leading edge of November 10 CME by constructing J-maps. We found that the
leading edge of November 10 CME interacted with the trailing edge of November 9
CME. We also estimated the kinematics of these features of the CMEs and found a
significant change in their dynamics after interaction. In in situ
observations, we identified distinct structures associated with interacted CMEs
and also noticed their heating and compression as signatures of CME-CME
interaction. Our analysis shows an improvement in arrival time prediction of
CMEs using their post-collision dynamics than using pre-collision dynamics.
Estimating the true masses and speeds of these colliding CMEs, we investigated
the nature of observed collision which is found to be close to perfectly
inelastic. The investigation also places in perspective the geomagnetic
consequences of the two CMEs and their interaction in terms of occurrence of
geomagnetic storm and triggering of magnetospheric substorms.
