**Answer:**

**608.4m/s **

**Explanation:**

We are given that

Mass of Sleigh,M=1200 kg

Speed of Sleigh,u=322 m/s

Speed of jet,u'=680 m/s

Mass of jet,m=4800 kg

Total mass=M+m=1200+4800=6000 kg

We have to find the final velocity of the two objects after the collision.

The collision is inelastic .

By using law of conservation of momentum

Using the formula

Hence, the final velocity of two objects after the collision=**608.4m/s **

It will increase..........................

Time in the universe vs the population

**Answer:**

**elastic collision**

An elastic collision occurs when the two objects "bounce" apart when they collide. Two rubber balls are a good example. In an elastic collision, both **momentum** and kinetic energy are conserved. Almost no energy is lost to sound, heat, or deformation.

I hope it's helpful!