The temperature of a body is raised from $20°\mathrm{C} \mathrm{to} 45°\mathrm{C}$. The rise in temperature of the body in the Fahrenheit scale is

The temperature on Celsius scale is $45°\mathrm{C}$, then corresponding temperature on the Fahrenheit scale is

A metal rod is placed on smooth horizontal surface at temperature 25$°C$. Now temperature of surroundings is increased up to 100$°C$, then during heating of rod

A: On a cold winter day an iron railing feels much colder to the touch than a wooden ceiling, though both are at the same temperature.

B: Wood removes thermal energy from our fingers much slower than iron does.

A: From the earth, heat transfer takes place mainly due to convection.

B: Heat from the sun is obtained in the form of IR rays of longer wavelength, which penetrates the atmosphere but heat radiated by the earth is IR rays of shorter wavelength, which is trapped by the atmosphere.

A faulty thermometer reads freezing point and boiling point of water as $10°C and 90°C$ respectively, the correct value of temperature as it reads $50°C$ is

A rod of length 40 cm is stretched between two rigid supports at zero tension. If the temperature is increased by 10°C, the stress produced in it is:

(Young's modulus, Y = 1.2x${10}^{12} \mathrm{N}/{\mathrm{m}}^2$, coefficient of linear expansion of rod = 2 x ${10}^{-5}$/°C)

An aluminum rod of length 2m held fixed in a horizontal position from its one end has the other end free. When the temperature of rod increases by 100°C, the thermal stress produced in the rod will be ($\mathrm{\alpha }$ = 1.6 x ${10}^{-6}$/°C)

A metal rod has a length of 100 cm and a cross-section area of 1 ${\mathrm{cm}}^2$. By raising its temperature from 0°C to 100°C so that it is not permitted to expand or bend, the tension developed in the rod is: ($\mathrm{Y} = {10}^{12} \mathrm{dyne}/{\mathrm{cm}}^2$ and $\mathrm{\alpha } = {10}^{-5}$/°C)

Two rods of different materials but identical geometry have thermal coefficients of linear expansion as $\mathrm{\alpha }$ and 5$\mathrm{\alpha }$. The rods are fixed between two rigid and massive walls and are heated to the same temperature. If there is no bending of the rods and the thermal stresses developed in them are equal, then the ratio of their Young's moduli is:

The quantities of heat required to raise the temperature of two solid copper spheres of radii ${\mathrm{r}}_1$ and ${\mathrm{r}}_2$ $({\mathrm{r}}_1=1.5 {\mathrm{r}}_2)$ through 1 K are in the ratio:

Three stars A, B, C have surface temperatures ${\mathrm{T}}_{\mathrm{A}}$, ${\mathrm{T}}_{\mathrm{B}}$, ${\mathrm{T}}_{\mathrm{C}}$ respectively. Star A appears bluish, star B appears reddish and star C yellowish. Hence,

The triple points of neon and carbon dioxide are 24.57 K and 216.55 K respectively. The value of these temperatures on Fahrenheit scales will be: 

The electrical resistance in ohms of a certain thermometer varies with temperature according to the approximate law:

$\mathrm{R}={\mathrm{R}}_0\left[1+\mathrm{\alpha }\left(\mathrm{T}-{\mathrm{T}}_0\right)\right]$

The resistance is 101.6 Ω at the triple-point of water 273.16 K, and 165.5 Ω at the normal melting point of lead (600.5 K). What is the temperature when the resistance is 123.4 Ω?

$$\begin{gathered} \left(1\right) 384.8 \mathrm{K} \\ \left(2\right) 486.8 \mathrm{K} \\ \left(3\right) 287.61 \mathrm{K} \\ \left(4\right) 185.61 \mathrm{K} \end{gathered}$$

A steel tape 1 m long is correctly calibrated for a temperature of 27.0 °C. The length of a steel rod measured by this tape is found to be 63.0 cm on a hot day when the temperature is 45.0 °C. What is the actual length of the steel rod on that day?

(Coefficient of linear expansion of steel = $1.20\times {10}^{-5} K^{-1}$).

$$\begin{gathered} \left(1\right) 62.485 \mathrm{cm} \\ \left(2\right) 60.762 \mathrm{cm} \\ \left(3\right) 65.935 \mathrm{cm} \\ \left(4\right) 63.013 \mathrm{cm} \end{gathered}$$

A large steel wheel is to be fitted onto a shaft of the same material. At 27 °C, the outer diameter of the shaft is 8.70 cm and the wheel's central hole has a diameter of 8.69 cm. The shaft is cooled using ‘dry ice’. At what temperature of the shaft does the wheel slip on the shaft?
(Assume the coefficient of linear expansion of the steel to be constant over the required temperature range  and \(\alpha\) steel = \(1.20 \times 10^5 K^{-1}\)$\left(\mathrm{)}\right)$

A geyser heats water flowing at the rate of 3.0 liters per minute from 27 °C to 77 °C. If the geyser operates on a gas burner, what is the fuel consumption rate if its heat of combustion is $4.0\times {10}^4 J/g$?

A hole is drilled in a copper sheet. The diameter of the hole is 4.24 cm at 27.0 °C. What is the change in the diameter of the hole when the sheet is heated to 227 °C?

(Co-efficient of linear expansion of copper= $1.70\times {10}^{-5} {\mathrm{K}}^{-1}$)

A brass wire 1.8 m long at 27 °C is held taut with a little tension between two rigid supports. If the wire is cooled to a temperature of –39 °C, what is the tension created in a wire with a diameter of 2.0 mm? (coefficient of linear expansion of brass = $2.0\times {10}^{-5} K^{-1}$, Young's modulus of brass=$0.91\times {10}^{11} Pa$)

The coefficient of volume expansion of glycerine is $49\times {10}^{-5} K^{-1}$. What is the fractional change in its density for a 30 °C rise in temperature?

$$\begin{gathered} \left(1\right) 1.44\times {10}^{-3} \\ \left(2\right) 1.57\times {10}^{-3} \\ \left(3\right) 1.57\times {10}^{-2} \\ \left(4\right) 1.44\times {10}^{-2} \end{gathered}$$

A body cools from 80 °C to 50 °C in 5 minutes. The time it takes to cool from 60 °C to 30 °C is: (The temperature of the surroundings is 20 °C)

A brass boiler has a base area of 0.15 $m^2$ and a thickness of 1.0 cm. It boils water at a rate of 6.0 kg/min when placed on a gas stove. What is the temperature of the part of the flame in contact with the boiler?

(Thermal conductivity of brass = $109 J s^{-1} m^{-1} K^{-1}$, the heat of vaporization of water =$2256\times {10}^3 J/kg$.)

$$\begin{gathered} \left(1\right) 237.{98}^{0}C \\ \left(2\right) {150}^{0}C \\ \left(3\right) 137.{98}^{0}C \\ \left(4\right) {100}^{0}C \end{gathered}$$

A ‘thermacole’ icebox is a cheap and efficient method for storing small quantities of

cooked food in summer in particular. A cubical icebox of side 30 cm has a thickness of

5.0 cm. If 4.0 kg of ice is put in the box, what is the amount of ice remaining after 6 h?

The outside temperature is 45 °C, and the coefficient of thermal conductivity of thermacole is $0.01 J s^{-1} m^{-1} K^{-1}.$$\left[Heat of fusion of water=335\times {10}^3 J k{g}^{-1}\right]$

A child of mass 30 kg running at a temperature of 101°F is given an antipyrin (i.e. 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 °F in 20 min, what is the average rate of extra evaporation caused, by the drug?

[Assume the evaporation mechanism to be the only way by which heat is lost. The mass of the child is 30 kg. The specific heat of the human body is approximately the same as that of water, and the latent heat of evaporation of water at that temperature is about 580 cal $g^{-1}$.]

A 10 kW drilling machine is used to drill a bore in a small aluminium block of mass 8.0 kg. How much is the rise in temperature of the block in 2.5 minutes?

(Assuming 50% of power is used up in heating the machine itself or lost to the surroundings? Specific heat of aluminium $=0.91 J g^{-1} K^{-1}$.)

$$\begin{gathered} \left(1\right) {103}^{0}C \\ \left(2\right) {109}^{0}C \\ \left(3\right) {211}^{0}C \\ \left(4\right) {197}^{0}C \end{gathered}$$

In an experiment on the specific heat of a metal, a 0.20 kg block of the metal at 150 °C is dropped in a copper calorimeter (of water equivalent of 0.025 kg) containing 150 $c{m}^3$ of water at 27 °C. The final temperature is 40 °C. The specific heat of the metal will be:

$\left(\mathrm{Heat} \mathrm{losses} \mathrm{to} \mathrm{the} \mathrm{surroundings} \mathrm{are} \mathrm{negligible}\right)$

$\begin{array}{rcl}& & 1. 0.40 J g^{-1} K^{-1}\\ & & 2. 0.43 J g^{-1} K^{-1}\\ & & 3. 0.54 J g^{-1} K^{-1}\\ & & 4. 0.61 J g^{-1} K^{-1}\end{array}$

Two metal spheres have radii r and 2r and they emit thermal radiations with maximum intensities at wavelengths $\mathrm{\lambda }$ and 2$\mathrm{\lambda }$ respectively. The respective ratio of the radiant energies emitted by them per second will be:

A copper block of mass 2.5 kg is heated in a furnace to a temperature of 500 °C and then placed on a large ice block. What is the maximum amount of ice that can melt?

(Specific heat of copper = $0.39 J g^{-1} K^{-1},$ the heat of fusion of water = 335 J/g)

Temperature is a measure of: