Question

The maximum safe speed of a vehicle on a circular track is $15km/h$. When the track becomes wet, the maximum safe speed is $10km/h$. The ratio of coefficient of friction of the dry track to that of wet track is

• A. $9:4$
  
• B. $3:2$
  
• C. $2:3$
  
• D. $1.5:1$
  

Answer 1

The correct option is A $9:4$

The maximum safe speed for a vehicle taking a turn on a curved banked road
is given by $v^2=\mu \ast rg$
hence $\frac{{\mu }_1}{{\mu }_2}=\frac{v_1^2}{v_2^2}={15}^2:{10}^2=9:4$