A car of mass $m$ when passes over top of convex bridge of radius of curvature $r,$ with a velocity $v,$ then the normal force exerted by the bridge on the car is 

Define $SI$ unit of force $N$. Define $CGS$ unit of force dyne.

A book is lying on the table. What is the angle between the action of the book on the table and the reaction of the table on the book ............ $^o$

A $100$ $Newton$ weight is suspended in a corner of a room by two cords $A$ and $B$ as shown in the figure below. The tension in the horizontal cord $A$ is ............ $N$

A football of radius $R$ is kept on a hole of radius $r (r < R)$ made on a plank kept horizontally. One end of the plank is now lifted so that it gets tilted making an angle $\theta$ from the horizontal as shown in the figure below. The maximum value of $\theta$ so that the football does not start rolling down the plank satisfies (figure is schematic and not drawn to scale) -

Two masses $m$ and $M$ are attached to the strings as shown in the figure. If the system is in equilibrium, then