Question

Three identical cars $A,B$ and $C$ are moving at the same speed on three bridges. The car A goes on a plane bridge, B on a bridge convex upward and C goes on a bridge concave upward. Let $F_A,F_B$ and $F_c$ be the normal forces exerted by the cars on the bridges when they are at the middle of bridges.

• A. $F_A$ is maximum of the three forces
• B. $F_B$ is maximum of the three forces
• C. $F_C$ is maximum of the three forces
• D. $F_A=F_B=F_C$

Answer 1

Answer: (C)

(i) For Plane Bridge

$F_A=N=Mg$

(ii) For Convex Upward Bridge

$F_B=N=Mg-\frac{M{v}^2}{r}$

(iii) For Concave Downward Bridge

$N-Mg=\frac{M{v}^2}{r}$

$F_C=\frac{M{v}^2}{r}+Mg$

$\therefore F_C>F_A>F_B$