Question

Consider a car moving along a straight horizontal road with a speed of 72 km/h. If the coefficient of kinetic friction between the tyres and the road is 0.5, the shortest distance in which the car can be stopped is $\left[ g = 10 \mathrm {~ms} ^ { - 2 } \right]$

• A. 30 m
• B. 40 m
• C. 72 m
• D. 20 m

Answer 1

Answer: (B)

40 m

Answer 2

$s = \frac { u ^ { 2 } } { 2 \mu g } = \frac { ( 20 ) ^ { 2 } } { 2 \times 0.5 \times 10 } = 40 \mathrm {~m}$