Answer:
4.44 kN in the opposite direction of acceleration.
Explanation:
Given that, the initial speed of the car is, [tex]u=20m/s[/tex]
And the mass of the car is, [tex]m=1000 kg[/tex]
The total distance covered by the car before stop, [tex]s=45m[/tex]
And the final speed of the car is, [tex]u=0m/s[/tex]
Now initial kinetic energy is,
[tex]KE_{i}=\frac{1}{2}mu^{2}[/tex]
Substitute the value of u and m in the above equation, we get
[tex]KE_{i}=\frac{1}{2}(1000kg)\times (20)^{2}\\KE_{i}=20000J[/tex]
Now final kinetic energy is,
[tex]KE_{f}=\frac{1}{2}mv^{2}[/tex]
Substitute the value of v and m in the above equation, we get
[tex]KE_{f}=\frac{1}{2}(1000kg)\times (0)^{2}\\KE_{i}=0J[/tex]
Now applying work energy theorem.
Work done= change in kinetic energy
Therefore,
[tex]F.S=KE_{f}-KE_{i}\\F\times 45=(0-200000)J\\F=\frac{-200000J}{45}\\ F=-4444.44N\\F=-4.44kN[/tex]
Here, the force is negative because the force and acceleration in the opposite direction.
