We will have that the momentum for both cars is respectively:
[tex]\begin{cases}t_1\colon p=m\cdot v \\ \\ t_2\colon_{}p=\frac{m\cdot v}{2}\end{cases}[/tex]
So, the momentrum for the second car is half the momentum for the first car.
***Explanation***
We remember that momentum is given by:
[tex]p=m\cdot v[/tex]
Here "p" is the momentum, "m" is the mass and "v" the velocity.
Now, for truck 1 we will have that the momentum will be:
[tex]p_1=m_1\cdot v[/tex]
Here "m1" is the mass of the first truck.
Now, for truck 2 we have that it has half the mass of truck one, so the momentum will be given by:
[tex]p_2=(\frac{m_1}{2})\cdot v\Rightarrow p_2=\frac{m_1\cdot v}{2}\Rightarrow p_2=\frac{p_1}{2}[/tex]
So, the momentum of truck 2 is half the momentum of the first truck.