We present 5-GHz MERLIN radio images of the microquasar GRS 1915+105 during two separate outbursts in 2001 March and 2001 July , following the evolution of the jet components as they move outwards from the core of the system .
Proper motions constrain the intrinsic jet speed to be > 0.57 c , but the uncertainty in the source distance prevents an accurate determination of the jet speed .
No deceleration is observed in the jet components out to an angular separation of \sim 300 mas .
Linear polarisation is observed in the approaching jet component , with a gradual rotation in position angle and a decreasing fractional polarisation with time .
Our data lend support to the internal shock model whereby the jet velocity increases leading to internal shocks in the pre-existing outflow before the jet switches off .
The compact nuclear jet is seen to re-establish itself within two days , and is visible as core emission at all epochs .
The energetics of the source are calculated for the possible range of distances ; a minimum power of 1–10 per cent L _ { Edd } is required to launch the jet .