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 ........ $N$

Write different type of common forces.

$A$ flexible chain of weight $W$ hangs between two fixed points $A$ & $B$ which are at he same horizontal level. The inclination of the chain with the horizontal at both the points of support is $\theta$ . What is the tension of the chain at the mid point? 

Two fixed frictionless inclined planes making an angle $30^o $ and $60^o $ with the vertical are shown in the figure. Two blocks $A$ and $B$ are placed on the two planes. What is the relative vertical acceleration of $A$ with respect to $B$?

The restoring force of a spring with a block attached to the free end of the spring is represented by

Ten one-rupee coins are put 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 elghth coin,

$(c)$ the reaction of the $6^{\text {th }}$ coin on the $7^{\text {th }}$ coin.