Adjoining figure shows a force of $40\, N$ acting at $30^o$ to the horizontal on a body of mass $5 \,kg$ resting on a smooth horizontal surface. Assuming that the acceleration of free-fall is $10\, ms^{-2}$, which of the following statements is (are) correct?

$[1]$ The horizontal force acting on the body is $20\, N$

$[2]$ The weight of the $5\, kg$ mass acts vertically downwards

$[3]$ The net vertical force acting on the body is $30\, N$

For given systen ${\theta _2}$ ....... $^o$ 

Three blocks of masses ${m_1},\,{m_2}$ and ${m_3}$ are connected by massless strings as shown on a frictionless table. They are pulled with a force ${T_3} = 40\,N$. If ${m_1} = 10\,kg,\,{m_2} = 6\,kg$ and ${m_3} = 4\,kg$, the tension ${T_2}$ will be ........ $N$

For a free body diagram shown in the figure, the four forces are applied in the ' $x$ ' and ' $y$ ' directions. What additional force must be applied and at what angle with positive $x$-axis so that the net acceleration of body is zero?

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.

If net force on a system is zero then