The coefficient of friction between the ground and the wheels of a car between the ground and the wheels of acar moving on a horizontal road is 0.5 If the car starts from rest , what is the minimum distance in which it can acquire a speed of `72 km // h` ? take `g = 10 ms^(-2)` .

Explanation

Here `mu=0.5, u=0`
`v=72 km h^-1=72 times 5/18=20 ms^-1`
As `mu=f/R=(ma)/(mg)=a/g`
`therefore a=mu g=0.5 times 10=5ms^-2`
As `v^2-u^2=2as`
`therefore (20)^2-(0)^2=2 times 5 times s or s=400/10=40m`