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

- A
Zero

- B
$mg$

- C
$mg + \frac{{m{v^2}}}{r}$

- D
$mg - \frac{{m{v^2}}}{r}$

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

A weight can be hung in any of following four ways by using same string. In which case is the string more likely to break is :-

What is Free body diagram ?

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?

A weight $M g$ is suspended from the middle of a rope whose ends are at the same level. The rope is no longer horizontal. The minimum tension required to completely straighten the rope is ......