An object will continue moving uniformly until

A rigid ball of mass, $m$ strikes a rigid wall at ${60}^o$ and gets reflected without any loss of speed as shown in the figure below. The value of impulse imparted by the wall on the ball will be


 

Figure represents the position-time graph of a body of mass $4 \mathrm{kg}$. Impulse $\left(\mathrm{kg} \mathrm{m} {\mathrm{s}}^{-1}\right)$ imparted to the body at $t=0$ is

Four identical beakers contain same amount of water as shown below.

Beaker $A$ contains only water. A lead ball is held submerged in the beaker $B$ by string from above. A same sized plastic ball, say a table tennis $\left(TT\right)$ ball, is held submerged in beaker $C$ by a string attached to a stand from outside. Beaker $D$ contains same sized $TT$ ball which is held submerged from a string attached to the bottom of the beaker. These beakers (without stand) are placed on weighing pans and register readings $w_A, w_B, w_C$ and $w_D$ for $A, B, C$ and $D$ respectively. Effects of the mass and volume of the stand and string are to be neglected.

The correct dimensional formula for impulse is given by

A block $A$ of mass $100 \mathrm{kg}$ rests on another block $B$ of mass $200 \mathrm{kg}$ and is tied to a wall as shown in the figure. The coefficient of friction between $A$ and $B$ is $0.2$ and that between $B$ and ground is $0.3$. The minimum force required to move the block $B$ is $\left(g=10 \mathrm{m} {\mathrm{s}}^{-2}\right)$