A car of mass 2000kg travelling at 5ms^{−1} collides with a minibus of mass 5000kg travelling in the opposite direction at 7ms^{−1}. The vehicles stick and move together after collision. If the collision lasts for 0.1seconds;

- Determine the velocity of the system after collision of 3 decimal places.
- Calculate the impulsive force on the minibus
- Calculate the change in kinetic energy of the system
- Explain the change in kinetic energy of the system