A motorcycle travels across an overbridge of radius R . The driver...

Let $\theta$ be the angle made by the radius vector of the motorcycle with the vertical.

The forces acting on the motorcycle along the radial direction are the component of weight $mg \cos\theta$ towards the center and the normal reaction $N$ away from the center.

The net force provides the necessary centripetal acceleration:

$mg \cos\theta - N = \dfrac{mv^2}{R}$

$N = mg \cos\theta - \dfrac{mv^2}{R}$

While the motorcycle is ascending the overbridge, it moves towards the highest point, so the angle $\theta$ decreases.

As $\theta$ decreases, the value of $\cos\theta$ increases.

Since the speed $v$ is constant, the term $\dfrac{mv^2}{R}$ remains constant.

Therefore, the normal force $N$ increases.