A motor car with a mass m moving with uniform speed v on a
(A) horizontal level bridge
(B) convex bridge
(C) concave bridge
The force exerted by the motor car when it is at centre of the bridge is

Options

A. highest in case (A)
B. lowest in case (B) and highest in case (C)
C. highest in case (B) and lowest in case (C)
D. same in three cases

Answer

B

Explanation

For (I) `mg=(mv^(2))/(r)`
Foe (II) ` mg-N_(A)=(mv^(2))/(r)`
` therefore N_(A)=mg -(mv^(2))/(r)`
For (III) ` N_(B)-mg=(mv^(2))/(r) `
` therefore NB=mg+(mv^(2))/(r)`
Thus ,`N_(B) gt N_(A)`
Thus normal force of reaction is more at the bottom of point