Question

The coefficient of friction between tyres and road is 0.4. find minimum distance covered before attaining a speed of 8m/s starting from rest is nearly

Answer 1

let us say that the static friction coefficient μ = 0.4.
let the mass of the vehicle be m.  acceleration due to gravity = g

Force on the vehicle = F > μ m g  = 4 m for the vehicle to start.

Let us ignore the rolling friction, as it is very small.
Then acceleration a = F/ m = 4 m/s²

We know  v² = 2 a s
=>    s = 8²/(2 a) = 4 meters

If there is a rolling friction then the vehicle takes longer distances to attain that speed of 8 m/s

Answer 2

Friction coefficient =a/g

0.4 = a/10

a = 4m/s^-

Given:

V= 8m/s u=0 a= 4m/s^2

As we know, v^2-u^2 = 2as

8^2 -0^2 = 2×4×s

64 -0 = 8s

S = 8m