Out of contact force and field force which force is conservative and which force is nonconservative ?

Give the magnitude and direction of the net force acting on

$(a)$ a drop of rain falling down with a constant speed,

$(b)$ a cork of mass $10\; g$ floating on water,

$(c)$ a kite skillfully held stationary in the sky,

$(d)$ a car moving with a constant velocity of $30\; km/h$ on a rough road,

$(e)$ a high-speed electron in space far from all material objects, and free of electric and magnetic fields.

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 ......

Two masses $M$ and $m$ are connected by a weightless string. They are pulled by a force $F$ on a frictionless horizontal surface. The tension in the string will be

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 :-

A body of weight $2\, kg$ is suspended as shown in the figure. The tension ${T_1}$ in the horizontal string (in kg wt) is