An automobile vehicle has a mass of $1500\ kg$. What must be the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of $1.7\ m s^{-2}$?

Given: An automobile vehicle has a mass of $1500\ kg$. 

To do: To calculate the force between the vehicle and road if the vehicle is to be stopped with a negative acceleration of $1.7\ m s^{-2}$.

Solution:
Here, the mass of the vehicle $m=1500\ kg.$

Negative acceleration $a=1.7\ ms^{-2}$

According to Newton's second law

Force $F=ma$

$=1500\ kg.\times(-1.7\ ms^{-2})$

$=-2550\ N$  [$-ve$ sign indicates the opposite direction]

Thus, the force acted to stop the vehicle is $2550\ N$ in opposite direction.