A) 50 m
B) 60 m
C) 40.8m
D) 80.16m
Correct Answer: C
Solution :
Free body diagram of automobile is shown By Newtons third law \[0.5=f=\mu R=\mu mg\] Where, m is the mass of automobile \[F=ma\] \[\mu mg=ma\] \[a=\mu g=0.5g\] Let automobile stops at a distance\[x,\]than from equation of motion \[{{v}^{2}}={{u}^{2}}-2ax\] \[v=0\,u=72\,km/h=72\times \frac{5}{18}=20\,m/s\] \[g=9.8\,m/{{s}^{2}}\] \[{{(0)}^{2}}={{(20)}^{2}}-2\times 0.5\times 9.8x\] \[x=\frac{20\times 20}{2\times 0.5\times 9.78}=40.8\,m\]You need to login to perform this action.
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