Question
Download Solution PDFA vehicle was stopped by fully jamming the breaks in 1.8 s and the skid marks measured 9 m. Determine the average skid resistance. Take g =10 m/s2 .
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
- Skid resistance is the force developed when a tire that is prevented from rotating slides along the pavement surface.
- Skid resistance depends on a pavement surface micro texture and macrotexture.
We know, according to the equation of motion final velocity is given by
\(v = u + at\) -- (1)
S = u × t + 0.5 a × t2-- (2)
Where, a = acceleration (m/sec2)
Average skid resistance coefficient is given by
\(f = - \frac{a}{g}\) -- (3)
Where,
g = acceleration due to gravity (m/sec2) = 9.81 m/sec2
f = average skid resistance
Calculation:
Initial Velocity, u = ?
Final Velocity, v = 0 kmph = 0 m/sec
Time, t = 1.8 sec, S = 9 m, g = 10 m/s2
From (1)
V = u + at
0 = u + a (1.8)
u = - 1.8 a - (A)
From (2)
S = u × t + 0.5 a × t2
9 = u × 1.8 + 0.5 × a × 1.82
9 = (-1.8a) × 1.8 + 0.5 × a × 1.82
a = - 5.556
From (3) Average skid resistance,
\(f = - \frac{a}{g} = \; - \frac{{ - (5.556)}}{{10}} = 0.556\)
Last updated on May 28, 2025
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