Given that force applied due to tree on car is 6000 N
and during the stop the acceleration is given as 2 m/s^2.
So here we can say that As per Newton's II law
[tex]F = m*a[/tex]
here F = force on car = 6000 N
a = acceleration of car = 2 m/s^2
now we can plug in all values above in the given equation
[tex]6000 = 2*m[/tex]
[tex]m = 3000 kg[/tex]
So here the mass of the car will be 3000 kg