Question

Find the braking force needed to bring a 4500 kg truck to a stop from a speed of 20 m/s in 9 s.

Answer 1

Given

Mass of the truck, m=4500 kg

Speed of th etruck, u=20 m/s

Time required , t=9 m/s

To find

The braking force

Step-by-step explanation

Since the car stops so the final velocity is v=0

Thus the acceleration of the truck is

`\begin{gathered} a=(v-u)/(t) \\ \Rightarrow a=(0-20)/(9)=-2.22m/s^2 \end{gathered}`

The negative sign says that the speed is decreasing i.e. decelaration is occuring

Thus the braking force is (considering only the magnitude)

`\begin{gathered} F=ma \\ \Rightarrow F=4500*2.22=9990\text{ N} \end{gathered}`

Conclusion

The braking force is 9990 N