when a body of mass $\mathrm{M}$ is attached to lower end of a wire (of length $\mathrm{L}$ ) whose upper end is fixed, then the elongation of the wire is $l$ .In this situation, mark out the correct statement $\left(\mathrm{s}\right)$

A metal wire of length $L,$area of cross-section $A$ and young's modulus $Y$ is stretched by a variable force $F$ such that $F$ is always slightly greater than the elastic forces of resistance in the wire. When the elongation of the wire is $l$

A heavy block of mass $150 \mathrm{kg}$ hangs with the help of three vertical wires of equal length and equal cross-sectional area as shown in figure. Wire is attached to the mid-point (centre of mass) of block. Take $Y_2=2Y_1.$ For this arrangement mark out the correct statement(s).

The wires $A$ and $B$ shown in the figure are made of the same material, and have radii $r_A$ and $r_B$ respectively. The block between them has a mass $m.$ When the force $F$ is $mg/3,$ one of the wires breaks:

A wire of length $L$ and cross-sectional area $\text{'}A\text{'}$ made of a material of Young's modulus $Y,$ is pulled by a constant force $F$ on a horizontal surface as shown in figure. Then

If a rod of length $l,$ very small area of cross section $A,$ Young’s modulus of elasticity $Y$ is acted upon by two parallel forces $3F$ and $F$ respectively (as shown) and placed on a smooth horizontal plane. If the elastic limit is not crossed and then to study the change in length of rod $(∆l)$ and it’s elastic potential energy $\left(U\right)$ the rod is segmented into four equal parts where magnitude of change in lengths are$∆l_1, ∆l_2, ∆l_3, ∆l_4$  and elastic potential energy stored in each segment are $U_1, U_2, U_3, U_4$ respectively as shown then which is/are correct?

Two opposite forces $F_1=120 \mathrm{N}$ and $F_2=80 \mathrm{N}$ act on an elastic plank of modulus of elasticity $Y=2\times {10}^{11} \mathrm{N}/{\mathrm{m}}^2$ and length $l=1 \mathrm{m}$ placed over a smooth horizontal surface. The cross-sectional area of the plank is $S=0.5{ \mathrm{m}}^2.$ The change in length of the plank is $n\times {10}^{-11} \mathrm{m}.$ Find the value of $n.$