An elevator cable can have a maximum stress of $7 \times 10^7\,N/m^2$ for appropriate safety factors. Its maximum upward acceleration is $1.5\,m/s^2$. If the cable has to support the total weight of $2000\,kg$ of a loaded elevator,the minimum area of cross-section of the cable should be ....... $cm^2$ $(g = 10\,m/s^2)$.

If the length of a wire is reduced to half,then it can hold the ......... load.

Match the type of elasticity involved:

System	Type of Elasticity
$(i)$ Suspension fibre of galvanometer	$(a)$ Linear
$(ii)$ Bending of beam	$(b)$ Shear
$(iii)$ Cutting piece of paper	$(c)$ Bulk
$(iv)$ Mechanical waves in fluid	$(d)$ Shear

What is the tangential stress on the cross-section $PQRS$?

$A$ string of cross-sectional area $4 \times 10^{-6} \, m^{2}$ and length $0.5 \, m$ is connected to a rigid body of mass $2 \, kg$. The body is rotated in a vertical circular path of radius $0.5 \, m$. The body acquires a speed of $5 \, m/s$ at the bottom of the circular path. The strain produced in the string when the body is at the bottom of the circle is $\dots \times 10^{-5}$. (Use Young's modulus $Y = 10^{11} \, N/m^{2}$ and $g = 10 \, m/s^{2}$)

In a series combination of copper and steel wires of same length and same diameter,a force is applied at one of their ends while the other end is kept fixed. The combined length is increased by $2 \ cm$. The wires will have ..........