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

(c) F_c is maximum of the three forces. 

Explanation:

Normal force on a plane bridge is equal to weight of the car. On a convex upward bridge due to the upward inertial force apparent weight reduces and so is the normal force on the vehicle. But at the middle of concave upward bridge this inertial force is downward making the apparent weight greater. Therefore the normal force is maximum in this case.