Two like parallel forces $20 \,N$ and $30 \,N$ act at the ends $A$ and $B$ of a rod $1.5 \,m$ long. The resultant of the forces will act at the point ........

Ten one-rupee coins are placed on top of each other on a table. Each coin has a mass $m$. Give the magnitude and direction of:
$(a)$ The force on the $7^{\text{th}}$ coin (counted from the bottom) due to all the coins on its top.
$(b)$ The force on the $7^{\text{th}}$ coin by the $8^{\text{th}}$ coin.
$(c)$ The reaction of the $6^{\text{th}}$ coin on the $7^{\text{th}}$ coin.

In the arrangement as shown,tension $T_2$ is ......... $N$ $\left(g=10\,m/s^2\right)$

The following forces start acting on a particle at rest at the origin of the coordinate system simultaneously: ${\vec F_1} = -4\hat i - 5\hat j + 5\hat k$,${\vec F_2} = 5\hat i + 8\hat j + 6\hat k$,${\vec F_3} = -3\hat i + 4\hat j - 7\hat k$,and ${\vec F_4} = 2\hat i - 3\hat j - 2\hat k$. The particle will move:

Three concurrent forces of the same magnitude are in equilibrium. What is the angle between the forces? Also,name the triangle formed by the forces as sides.

$A$ $1 \text{ N}$ pendulum bob is held at an angle $\theta$ from the vertical by a $2 \text{ N}$ horizontal force $F$ as shown in the figure. The tension in the string supporting the pendulum bob (in newton) is