Question:
A vehicle was stopped in two seconds by fully jamming the brakes. The skid mark measured \(9.8\) metres. The average skid resistance coefficient will be
A vehicle was stopped in two seconds by fully jamming the brakes. The skid mark measured \(9.8\) metres. The average skid resistance coefficient will be
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For skid resistance,
\[
\boxed{
f=\frac{V^2}{2gS}
}
\]
where \(V\) is the speed just before braking and \(S\) is the skid distance.
Updated On: Jul 23, 2026
- \(0.7\)
- \(0.5\)
- \(0.4\)
- \(0.25\)
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Verified By Collegedunia
The Correct Option is B
Solution and Explanation
Concept:
For a vehicle coming to rest under uniform deceleration,
\[
S=\frac{ut}{2}
\]
where
\[
S=\text{Skid distance},
\]
\[
u=\text{Initial speed},
\]
\[
t=\text{Time to stop}.
\]
The coefficient of skid resistance is
\[
\boxed{
f=\frac{u^2}{2gS}
}
\]
Step 1: Calculate the initial speed. Given, \[ S=9.8\text{ m},\qquad t=2\text{ s} \] Using \[ S=\frac{ut}{2}, \] \[ 9.8=\frac{u\times2}{2} \] \[ u=9.8\text{ m/s} \]
Step 2: Calculate the skid resistance coefficient. \[ f = \frac{9.8^2}{2\times9.8\times9.8} = \frac{1}{2} = 0.5 \] Hence, \[ \boxed{f=0.5} \] Therefore, the correct option is \[ \boxed{(B)\;0.5.} \]
Step 1: Calculate the initial speed. Given, \[ S=9.8\text{ m},\qquad t=2\text{ s} \] Using \[ S=\frac{ut}{2}, \] \[ 9.8=\frac{u\times2}{2} \] \[ u=9.8\text{ m/s} \]
Step 2: Calculate the skid resistance coefficient. \[ f = \frac{9.8^2}{2\times9.8\times9.8} = \frac{1}{2} = 0.5 \] Hence, \[ \boxed{f=0.5} \] Therefore, the correct option is \[ \boxed{(B)\;0.5.} \]
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