An object is subjected to a force in the north-east direction. To balance this force,a second force should be applied in the direction:

$ABC$ is an equilateral triangle. The length of each side is $a$ and the centroid is point $O$. Find $\overrightarrow{AB} + \overrightarrow{BC} + \overrightarrow{CA} = \ldots \ldots$.

What is a unit vector? Explain.

If $|\vec{A}+\vec{B}|=|\vec{A}-\vec{B}|$,then the angle between vector $\vec{A}$ and $\vec{B}$ is: (in $^{\circ}$)

Two forces $F_1 = 1\,N$ and $F_2 = 2\,N$ act along the lines $x = 0$ and $y = 0$ respectively. Then the resultant of forces would be

If water at $100^\circ C$ cools in $10$ minutes to $80^\circ C$ and to $65^\circ C$ in the next $10$ minutes, then the room temperature will be ...