A thin rod having a length of $1\; m$ and area of cross-section $3 \times 10^{-6}\,m ^2$ is suspended vertically from one end. The rod is cooled from $210^{\circ}\,C$ to $160^{\circ}\,C$. After cooling, a mass $M$ is attached at the lower end of the rod such that the length of rod again becomes $1\,m$. Young's modulus and coefficient of linear expansion of the rod are $2 \times 10^{11} Nm ^{-2}$ and $2 \times 10^{-5} K ^{-1}$, respectively. The value of $M$ is $.......kg .\left(\right.$ Take $\left.g=10\,m s ^{-2}\right)$
$60$
$59$
$58$
$57$
A student records the initial length $l$, change in temperature $\Delta T$ and change in length $\Delta l$ of a rod as follows :
S.No. | $l(m)$ | $\Delta T{(^o}C)$ | $\Delta l(m)$ |
$(1)$ | $2$ | $10$ | $4\times 10^{-4}$ |
$(2)$ | $1$ | $10$ | $4\times 10^{-4}$ |
$(3)$ | $2$ | $20$ | $2\times 10^{-4}$ |
$(4)$ | $3$ | $10$ | $6\times 10^{-4}$ |
If the first observation is correct, what can you say about observations $2,\,3$ and $4$.
Two metal strips that constitute a thermostat must necessarily differ in their
Where $\alpha _V$ is greater among alcohol and mercury ?
The coefficient of volume expansion of glycerin is $49 \times 10^{-5} \,K ^{-1}$. The fractional change in the density on a $30^{\circ} C$ rise in temperature is ..........
A metal rod of Young's modulus $Y$ and coefficient of thermal expansion $\alpha$ is held at its two ends such that its length remains invariant. If its temperature is raised by $t^{\circ} C$, the linear stress developed in it is