Define $SI$ unit of force $N$. Define $CGS$ unit of force dyne.

One end of a string of length $l$ is connected to a particle of mass $m$ and the other to a small peg on a smooth horizontal table. If the particle moves in a circle with speed $v$ the net force on the particle (directed towards the centre) is :

$(i) \;T,$ $(ii)\; T-\frac{m v^{2}}{l},$ $(iii)\;T+\frac{m v^{2}}{l},$ $(iv) \;0$

$T$ is the tension in the string. [Choose the correct alternative].

A rope of length $5\,m$ is kept on frictionless surface and a force of $5\,N$ is applied to one of its end. Find tension in the rope at $1\,m $ from this end ......... $N$

When a body is stationary

A rope of mass $5 \,kg$ is hanging between two supports as shown alongside. The tension at the lowest point of the rope is close to ........... $N$ (take, $g=10 \,m / s ^{2}$ )

A jet of liquid of cross-sectional area $'a'$ strikes a wall making angle $\theta $ with wall. The water strikes with the wall with velocity $v$ and rebounds elastically. If density of liquid be $\rho $, the normal force on the wall is