Q.

A circular racetrack of radius 300 m is banked at an angle of 15°. The coefficient of friction between the wheels of a race car and the road is 0.2. The optimum speed of the race car to avoid wear and tear on its tyres is  (Take tan15°=0.27, g=10 m s-2)

1 103 m s-1  
2 910 m s-1  
3 10 m s-1  
4 210 m s-1  

Ans.

(2)

Here, R=300 m, θ=15°, g=10 m s-2, μ=0.2

The optimum speed of the car to avoid wear and tear is given by

v=Rg tanθ=300×10×tan15°=810=910 m s-1