Answer:
Speed of the wreck after the collision is 65 km/h
Explanation:
When a car hits truck and sticks together, the collision would be totally inelastic. Since the both the vehicles locked together, they have the same final velocity.
Mass of car [tex]m_{1}=1200 kg[/tex]
Mass of truck [tex]m_{2}=2800 kg[/tex]
Initial speed of the car [tex]u_{1}=100 km /h[/tex]
Initial speed of the truck [tex]u_{2}=50 km /h[/tex]
The final velocity of the wreck will be
[tex]m_{1}u_{1}+m_{2}u_{2}=m_{1}v_{1}+m_{2}v_{2}[/tex]
since final speed are same, [tex]v_{1}=v_{2}=v[/tex]
[tex]m_{1}u_{1}+m_{2}u_{2}=(m_{1}+m_{2})v[/tex]
[tex]1200\times 100 +2800 \times 50 =(1200+2800)v\\v=\frac{260000}{4000} \\v=65 km/h[/tex]
