Ametal wire is clamped between two vertical walls.At $20 ^o C$ the unstrained length of the wire is exactly equal to the separation between walls. If the temperature of the wire is decreased the graph between elastic energy density $(u)$ and temperature $(T)$ of the wire is
What is called change of state of matter ?
Answer the following questions based on the $P-T$ phase diagram of $CO _{2}$
$(a)\;CO _{2}$ at $1\; atm$ pressure and temperature $-60\,^{\circ} C$ is compressed isothermally. Does it go through a llquid phase?
$(b)$ What happens when $CO _{2}$ at $4\; atm$ pressure is cooled from room temperature at constant pressure?
$(c)$ Describe qualitatively the changes in a given mass of solid $CO _{2}$ at $10 \;atm$ pressure and temperature $-65\,^{\circ} C$ as it is heated up to room temperature at constant pressure.
$(d)\;CO_{2}$ is heated to a temperature $70\,^{\circ} C$ and compressed isothermally. What changes in its properties do you expect to observe?
What is vapourization ? What is normal boiling point ?
A child running a temperature of $101\,^{\circ} F$ is given an antipyrin (i.e. a medicine that lowers fever) which causes an increase in the rate of evaporation of sweat from his body. If the fever is brought down to $98\,^{\circ} F$ in $20$ minutes, what is the average rate of extra evaporation caused, by the drug (in $g/min$). Assume the evaporation mechanism to be the only way by which heat is lost. The mass of the child is $30\; kg$. The spectfic heat of human body is approximately the same as that of water, and latent heat of evaporation of water at that temperature is about $580\; cal \;g^{-1}$.
A closed bottle containing water at $30^{\circ} C$ is open on the surface of the moon. Then,