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Complete Syllabus Question Paper
Grade 11 : Physics - Thermal Properties (Set 3)— Questions & Detailed Solutions
Q1
A steel rod of Young's modulus $Y = 2 \times 10^{11}\text{ N/m}^2$ and coefficient of linear expansion $\alpha = 1.2 \times 10^{-5}\text{ K}^{-1}$ is clamped rigidly between two fixed vertical walls.
If the temperature of the rod is increased by $50^\circ\text{C}$, what is the thermal stress developed inside the rod?
(A)
60 MPa
(B)
120 MPa
(C)
180 MPa
(D)
240 MPa
Q2
In a calorimetry experiment, 40 g of ice at $0^\circ\text{C}$ is mixed with 40 g of liquid water at $40^\circ\text{C}$ in an insulated vessel.Given latent heat of fusion $L_f = 80\text{ cal/g}$ and specific heat of water $c = 1\text{ cal/g}^\circ\text{C}$, what is the final state of the mixture?
In a calorimetry experiment, 40 g of ice at $0^\circ\text{C}$ is mixed with 40 g of liquid water at $40^\circ\text{C}$ in an insulated vessel.
Given latent heat of fusion $L_f = 80\text{ cal/g}$ and specific heat of water $c = 1\text{ cal/g}^\circ\text{C}$, what is the final state of the mixture?
(A)
$0^\circ\text{C}$ with 20 g ice remaining
(B)
$0^\circ\text{C}$ with 0 g ice remaining
(C)
$5^\circ\text{C}$ all liquid water
(D)
$10^\circ\text{C}$ all liquid water
Q3
A composite slab consists of two layers of equal thickness $d$ placed end to end with thermal conductivities $K_1 = 100\text{ W/m}\cdot\text{K}$ and $K_2 = 300\text{ W/m}\cdot\text{K}$.What is the effective thermal conductivity $K_{eq}$ of the composite slab for series heat flow?
A composite slab consists of two layers of equal thickness $d$ placed end to end with thermal conductivities $K_1 = 100\text{ W/m}\cdot\text{K}$ and $K_2 = 300\text{ W/m}\cdot\text{K}$.
What is the effective thermal conductivity $K_{eq}$ of the composite slab for series heat flow?
(A)
$150\text{ W/m}\cdot\text{K}$
(B)
$200\text{ W/m}\cdot\text{K}$
(C)
$225\text{ W/m}\cdot\text{K}$
(D)
$250\text{ W/m}\cdot\text{K}$
Q4
According to Newton's law of cooling, a body cools from $80^\circ\text{C}$ to $60^\circ\text{C}$ in 5 minutes when the surrounding temperature is $20^\circ\text{C}$.Assuming linear approximation, how long will it take for the body to cool from $60^\circ\text{C}$ to $40^\circ\text{C}$ under the same conditions?
According to Newton's law of cooling, a body cools from $80^\circ\text{C}$ to $60^\circ\text{C}$ in 5 minutes when the surrounding temperature is $20^\circ\text{C}$.
Assuming linear approximation, how long will it take for the body to cool from $60^\circ\text{C}$ to $40^\circ\text{C}$ under the same conditions?
(A)
5.0 min
(B)
6.5 min
(C)
8.33 min
(D)
10.0 min
Q5
A solid copper sphere of radius $R$ at absolute temperature $T$ radiates thermal power $P$. If the radius of the sphere is doubled to $2R$ and its absolute temperature is doubled to $2T$, what is the new total radiated power $P'$?
A solid copper sphere of radius $R$ at absolute temperature $T$ radiates thermal power $P$. If the radius of the sphere is doubled to $2R$ and its absolute temperature is doubled to $2T$, what is the new total radiated power $P'$?
(A)
$8P$
(B)
$16P$
(C)
$32P$
(D)
$64P$
Q6
The wavelength of maximum radiation intensity emitted by a black body at temperature 2000 K is $\lambda_1 = 1.5\ \mum$. What will be the peak wavelength $\lambda_2$ if the temperature is raised to 3000 K?
The wavelength of maximum radiation intensity emitted by a black body at temperature 2000 K is $\lambda_1 = 1.5\ \mum$. What will be the peak wavelength $\lambda_2$ if the temperature is raised to 3000 K?
(A)
$0.75\ \mum$
(B)
$1.0\ \mum$
(C)
$1.25\ \mum$
(D)
$2.25\ \mum$
Q7
A pendulum clock with a brass rod ($\alpha = 2 \times 10^{-5}\text{ K}^{-1}$) keeps accurate time at $20^\circ\text{C}$.If the ambient temperature increases to $30^\circ\text{C}$, how much time does the clock lose or gain per day?
A pendulum clock with a brass rod ($\alpha = 2 \times 10^{-5}\text{ K}^{-1}$) keeps accurate time at $20^\circ\text{C}$.
If the ambient temperature increases to $30^\circ\text{C}$, how much time does the clock lose or gain per day?
(A)
Gains 8.64 s
(B)
Loses 8.64 s
(C)
Loses 4.32 s
(D)
Gains 4.32 s
Q8
A glass flask ($\alpha_{glass} = 1 \times 10^{-5}\text{ K}^{-1}$) of volume $1000cm^3$ is completely filled with liquid at $20^\circ\text{C}$. The real cubical expansion coefficient of the liquid is $\gamma_r = 6 \times 10^{-4}\text{ K}^{-1}$. What volume of liquid overflows when heated to $70^\circ\text{C}$?
A glass flask ($\alpha_{glass} = 1 \times 10^{-5}\text{ K}^{-1}$) of volume $1000cm^3$ is completely filled with liquid at $20^\circ\text{C}$. The real cubical expansion coefficient of the liquid is $\gamma_r = 6 \times 10^{-4}\text{ K}^{-1}$. What volume of liquid overflows when heated to $70^\circ\text{C}$?
(A)
$15.0cm^3$
(B)
$28.5cm^3$
(C)
$30.0cm^3$
(D)
$33.5cm^3$
Q9
A faulty thermometer has its lower fixed point at $5^\circ\text{C}$ and upper fixed point at $95^\circ\text{C}$. When this thermometer reads $41^\circ\text{C}$, what is the correct reading on the standard Celsius scale?
A faulty thermometer has its lower fixed point at $5^\circ\text{C}$ and upper fixed point at $95^\circ\text{C}$. When this thermometer reads $41^\circ\text{C}$, what is the correct reading on the standard Celsius scale?
(A)
$35^\circ\text{C}$
(B)
$40^\circ\text{C}$
(C)
$45^\circ\text{C}$
(D)
$48^\circ\text{C}$
Q10
On a frozen lake surface, an ice sheet of thickness 2 cm forms in 10 minutes when atmospheric temperature is $-10^\circ\text{C}$.How much additional time is required for the ice layer to grow from a thickness of 2 cm to 4 cm?
On a frozen lake surface, an ice sheet of thickness 2 cm forms in 10 minutes when atmospheric temperature is $-10^\circ\text{C}$.
How much additional time is required for the ice layer to grow from a thickness of 2 cm to 4 cm?
(A)
10 min
(B)
20 min
(C)
30 min
(D)
40 min
Q11
Two cylindrical rods of the same metal have lengths in ratio $1:2$ and radii in ratio $2:1$. If they are connected in parallel across identical temperature differences, what is the ratio of heat current through rod 1 to rod 2 ($H_1 / H_2$)?
Two cylindrical rods of the same metal have lengths in ratio $1:2$ and radii in ratio $2:1$. If they are connected in parallel across identical temperature differences, what is the ratio of heat current through rod 1 to rod 2 ($H_1 / H_2$)?
(A)
$1 : 8$
(B)
$2 : 1$
(C)
$4 : 1$
(D)
$8 : 1$
Q12
A copper block of mass 0.84 kg at $100^\circ\text{C}$ is placed into a large cavity in an ice block at $0^\circ\text{C}$. If specific heat of copper is $400\text{ J/kg}\cdot\text{K}$ and latent heat of fusion of ice is $3.36 \times 10^5\text{ J/kg}$, what mass of ice melts?
A copper block of mass 0.84 kg at $100^\circ\text{C}$ is placed into a large cavity in an ice block at $0^\circ\text{C}$. If specific heat of copper is $400\text{ J/kg}\cdot\text{K}$ and latent heat of fusion of ice is $3.36 \times 10^5\text{ J/kg}$, what mass of ice melts?
(A)
50 g
(B)
100 g
(C)
150 g
(D)
200 g
Q13
A body radiates energy at rate $P$ in vacuum at temperature 300 K. If its absolute temperature is tripled to 900 K, what is the new rate of energy radiation according to Stefan-Boltzmann law?
A body radiates energy at rate $P$ in vacuum at temperature 300 K. If its absolute temperature is tripled to 900 K, what is the new rate of energy radiation according to Stefan-Boltzmann law?
(A)
$9P$
(B)
$27P$
(C)
$81P$
(D)
$243P$
Q14
A copper calorimeter of mass 100 g ($c_{Cu} = 0.1\text{ cal/g}^\circ\text{C}$) contains 140 g of water at $15^\circ\text{C}$.If 50 g of water at $55^\circ\text{C}$ is added to the calorimeter, what is the final thermal equilibrium temperature?
A copper calorimeter of mass 100 g ($c_{Cu} = 0.1\text{ cal/g}^\circ\text{C}$) contains 140 g of water at $15^\circ\text{C}$.
If 50 g of water at $55^\circ\text{C}$ is added to the calorimeter, what is the final thermal equilibrium temperature?
(A)
$20^\circ\text{C}$
(B)
$25^\circ\text{C}$
(C)
$30^\circ\text{C}$
(D)
$35^\circ\text{C}$
Q15
A hollow spherical shell made of aluminum has inner radius $r_1$ and outer radius $r_2$. When the entire shell is heated uniformly, what happens to $r_1$ and $r_2$?
A hollow spherical shell made of aluminum has inner radius $r_1$ and outer radius $r_2$. When the entire shell is heated uniformly, what happens to $r_1$ and $r_2$?
(A)
$r_1$ increases and $r_2$ decreases
(B)
$r_1$ decreases and $r_2$ increases
(C)
Both $r_1$ and $r_2$ increase proportionally
(D)
$r_1$ remains constant while $r_2$ increases
Q16
A conducting rod of length $L$ and cross-sectional area $A$ has position-dependent thermal conductivity $K(x) = K_0 (1 + x/L)$ along its length.If the ends at $x=0$ and $x=L$ are maintained at steady temperatures $T_1$ and $T_2$ ($T_1 > T_2$), what is the steady-state rate of heat flow $H$?
A conducting rod of length $L$ and cross-sectional area $A$ has position-dependent thermal conductivity $K(x) = K_0 (1 + x/L)$ along its length.
If the ends at $x=0$ and $x=L$ are maintained at steady temperatures $T_1$ and $T_2$ ($T_1 > T_2$), what is the steady-state rate of heat flow $H$?
(A)
$\frac{K_0 A (T_1 - T_2)}{L \ln 2}$
(B)
$\frac{K_0 A (T_1 - T_2)}{L} \ln 2$
(C)
$\frac{2 K_0 A (T_1 - T_2)}{L}$
(D)
$\frac{K_0 A (T_1 - T_2)}{2L}$
Q17
The average solar radiant energy reaching Earth's surface per unit area per unit time is the solar constant $S$. If the mean distance between Earth and Sun were halved, what would be the new solar constant $S'$?
The average solar radiant energy reaching Earth's surface per unit area per unit time is the solar constant $S$. If the mean distance between Earth and Sun were halved, what would be the new solar constant $S'$?
(A)
$S/4$
(B)
$S/2$
(C)
$2S$
(D)
$4S$
Q18
A bimetallic strip of total thickness $d$ consists of two thin metal strips of equal thickness bonded together, with linear expansion coefficients $\alpha_1$ and $\alpha_2$ (where $\alpha_1 > \alpha_2$).When heated by temperature difference $\Delta T$, the strip bends into a circular arc. What is the radius of curvature $R$ of the strip?
A bimetallic strip of total thickness $d$ consists of two thin metal strips of equal thickness bonded together, with linear expansion coefficients $\alpha_1$ and $\alpha_2$ (where $\alpha_1 > \alpha_2$).
When heated by temperature difference $\Delta T$, the strip bends into a circular arc. What is the radius of curvature $R$ of the strip?
(A)
$R \approx \frac{d}{(\alpha_1 - \alpha_2) \Delta T}$
(B)
$R \approx \frac{d (\alpha_1 - \alpha_2)}{\Delta T}$
(C)
$R \approx \frac{2d}{(\alpha_1 + \alpha_2) \Delta T}$
(D)
$R \approx \frac{d}{\alpha_1 \alpha_2 \Delta T}$
Q19
Dry steam at $100^\circ\text{C}$ is passed into 500 g of liquid water at $20^\circ\text{C}$ inside a calorimeter of negligible heat capacity.Given $L_v = 540\text{ cal/g}$ and $c_w = 1\text{ cal/g}^\circ\text{C}$, what is the final mass of liquid water in the container at equilibrium?
Dry steam at $100^\circ\text{C}$ is passed into 500 g of liquid water at $20^\circ\text{C}$ inside a calorimeter of negligible heat capacity.
Given $L_v = 540\text{ cal/g}$ and $c_w = 1\text{ cal/g}^\circ\text{C}$, what is the final mass of liquid water in the container at equilibrium?
(A)
500 g
(B)
574 g
(C)
600 g
(D)
426 g
Q20
Prevost's Theory of Heat Exchange:
Statement I: All bodies above absolute zero emit thermal radiation continuously.
Statement II: A body in thermal equilibrium with its surroundings ceases radiation exchange.Which statement correctly describes a body in thermal equilibrium with its surroundings?
Prevost's Theory of Heat Exchange:
Statement I: All bodies above absolute zero emit thermal radiation continuously.
Statement II: A body in thermal equilibrium with its surroundings ceases radiation exchange.
Statement I: All bodies above absolute zero emit thermal radiation continuously.
Statement II: A body in thermal equilibrium with its surroundings ceases radiation exchange.
Which statement correctly describes a body in thermal equilibrium with its surroundings?
(A)
It stops emitting thermal radiation completely
(B)
It emits and absorbs thermal radiation at equal rates
(C)
It only absorbs radiation without emitting any
(D)
Its emissivity becomes exactly equal to zero

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