Q.

A car of mass 'm' moves on a banked road having radius 'r' and banking angle θ. To avoid slipping from banked road, the maximum permissible speed of the car is v0. The coefficient of friction μ between the wheels of the car and the banked road is          [2025]

1 μ=v02+rg tan θrgv02tan θ  
2 μ=v02+rg tan θrg+v02tan θ  
3 μ=v02rg tan θrg+v02tan θ  
4 μ=v02rg tan θrgv02tan θ  

Ans.

(3)

Given maximum possible speed =v0

For this

So, N=mg cos θ+mv02rsin θ

fr =μN=μ(mg cos θ+mv02rsin θ)

And mv02rcos θ=mg sin θ+ fr

 mv02rcos θmg sin θ=μ(mg cos θ+mv02rsin θ)

 (v02gr tan θ)=μ(v02tan θ+gr)

 μ=v02gr tan θgr+v02tan θ