Determine the shortest time possible for the rearwheel drive

Determine the shortest time possible for the rear-wheel drive, 2-Mg truck to achieve a speed of 19 m/s with a constant acceleration starting from rest. The coefficient of static friction between the wheels and the road surface is mu_s = 0.7. The front wheels are free to roll. Neglect the mass of the wheels.

Solution

Answer -

Acceleration(a) = (Coeffcient of friction x Total Normal Force) / Total Mass

a = 1.4 x g [ g = acceleration due to gravity ] [ x= multiplication term]

Now using basic equation for constant acceleration

v = u + at [ v&u are final and initial velocities, t is time]

t = v-u/a

t = 19/(1.4 x 9.8)

t = 1.3 sec