The net force of the car is 6000 N.
Why?
To calculate the net force of the car during the given time, we first need to calculate its acceleration, and then, use Newton's Second Law equation to calculate the net force.
We can calculate the acceleration of the car during the given tieme using the following equation:
![a=(v-v_(o))/(time)](https://img.qammunity.org/2020/formulas/physics/middle-school/xlm6sg0sqc634sf8ewai2hsoog1oh5070w.png)
Substituting the given information, we have:
![a=(30(m)/(s) -15(m)/(s) )/(10s)=(15(m)/(s) )/(10s)=1.5(m)/(s^(2) )](https://img.qammunity.org/2020/formulas/physics/middle-school/otlzzggp8mgs330evan56257ti314l3xsa.png)
Now that we have calculated the acceleration, we can calculate the net force:
![Force=mass*acceleration\\\\Force=4000kg*1.5(m)/(s^(2))=6000(kg.m)/(s^(2))=6000N](https://img.qammunity.org/2020/formulas/physics/middle-school/mpkhnkyd61308inr9pmawt0r0itk3ac7d4.png)
Hence, we have that the net force is equal to 6000N.
Have a nice day!