Grade 11 : Physics - Thermal Properties (Set 7)

Question 1

Convert a temperature reading of $50^\circ ext{C}$ to the Fahrenheit and Kelvin scales.

Accepted Answer

A) $122^\circ	ext{F}$ and 323.15 K

Answer

B) $112^\circ	ext{F}$ and 313.15 K

Answer

C) $122^\circ	ext{F}$ and 313.15 K

Answer

D) $90^\circ	ext{F}$ and 323.15 K

Question 2

A brass rod has a length of 2.0 m at $20^\circ ext{C}$. If the coefficient of linear expansion of brass is $\alpha = 2.0 imes 10^{-5} ext{ K}^{-1}$, calculate the increase in length when heated to $120^\circ ext{C}$.

Accepted Answer

B) 4.0 mm

Answer

A) 2.0 mm

Answer

C) 0.4 mm

Answer

D) 8.0 mm

Question 3

For an isotropic solid material, what is the theoretical ratio between the coefficient of linear expansion ($\alpha$), coefficient of area expansion ($\beta$), and coefficient of volume expansion ($\gamma$)?

Accepted Answer

A) $1 : 2 : 3$

Answer

B) $1 : 1 : 1$

Answer

C) $3 : 2 : 1$

Answer

D) $1 : 3 : 2$

Question 4

A steel rod of cross-sectional area $4.0 imes 10^{-4} m^2$ is rigidly clamped at both ends at $25^\circ ext{C}$. If Young's modulus $Y = 2.0 imes 10^{11} ext{ N/m}^2$ and coefficient of linear expansion $\alpha = 1.2 imes 10^{-5} ext{ K}^{-1}$, find the tension developed in the rod when cooled to $5^\circ ext{C}$.

Accepted Answer

B) 19.2 kN

Answer

A) 9.6 kN

Answer

C) 38.4 kN

Answer

D) 4.8 kN

Question 5

A pendulum clock made of steel ($\alpha = 1.2 imes 10^{-5} ext{ K}^{-1}$) keeps accurate time at $20^\circ ext{C}$. If the ambient temperature increases to $30^\circ ext{C}$, how much time does the clock gain or lose per day?

Accepted Answer

B) Loses 5.184 s/day

Answer

A) Gains 5.184 s/day

Answer

C) Loses 10.368 s/day

Answer

D) Gains 2.592 s/day

Question 6

A container holds 100 g of ice at $0^\circ ext{C}$. If 100 g of liquid water at $80^\circ ext{C}$ is poured into it, what will be the final temperature of the mixture at thermal equilibrium? (Latent heat of fusion of ice $L_f = 80 ext{ cal/g}$, specific heat of water $c = 1 ext{ cal/(g}\cdot^\circ ext{C)}$)

Accepted Answer

A) $0^\circ	ext{C}$

Answer

B) $10^\circ	ext{C}$

Answer

C) $20^\circ	ext{C}$

Answer

D) $40^\circ	ext{C}$

Question 7

A calorimeter of mass 100 g is made of a metal with specific heat capacity $0.10 ext{ cal/(g}\cdot^\circ ext{C)}$. What is the water equivalent of this calorimeter?

Accepted Answer

B) 10 g

Answer

A) 100 g

Answer

C) 1 g

Answer

D) 50 g

Question 8

Calculate the total heat required to convert 50 g of ice at $0^\circ ext{C}$ into steam at $100^\circ ext{C}$. ($L_f = 80 ext{ cal/g}$, $c_{ ext{water}} = 1 ext{ cal/(g}\cdot^\circ ext{C)}$, $L_v = 540 ext{ cal/g}$)

Accepted Answer

A) 36 kcal

Answer

B) 27 kcal

Answer

C) 31 kcal

Answer

D) 42 kcal

Question 9

A composite wall is formed by two layers of equal thickness $d$ having thermal conductivities $K_1$ and $K_2$. What is the equivalent thermal conductivity $K_{eq}$ for steady heat flow perpendicular to the layers (in series)?

Accepted Answer

B) $\frac{2 K_1 K_2}{K_1 + K_2}$

Answer

A) $\frac{K_1 K_2}{K_1 + K_2}$

Answer

C) $\frac{K_1 + K_2}{2}$

Answer

D) $\sqrt{K_1 K_2}$

Question 10

Two metal bars are joined end-to-end:
[100°C] --- Bar 1 (K1 = 300 W/m K) --- Junction (Tj) --- Bar 2 (K2 = 100 W/m K) --- [0°C]

Two metal rods of equal length and equal cross-sectional area are connected in series as shown above. Their thermal conductivities are $300 ext{ W/(m}\cdot ext{K)}$ and $100 ext{ W/(m}\cdot ext{K)}$. If the open ends are kept at $100^\circ ext{C}$ and $0^\circ ext{C}$, what is the junction temperature $T_j$?

Accepted Answer

C) $75^\circ	ext{C}$

Answer

A) $50^\circ	ext{C}$

Answer

B) $60^\circ	ext{C}$

Answer

D) $25^\circ	ext{C}$

Question 11

What is the dimensional formula for thermal conductivity ($K$)?

Accepted Answer

A) $[M^1 L^1 T^{-3} K^{-1}]$

Answer

B) $[M^1 L^2 T^{-3} K^{-1}]$

Answer

C) $[M^1 L^1 T^{-2} K^{-1}]$

Answer

D) $[M^1 L^{-1} T^{-2} K^{-1}]$

Question 12

A black body at absolute temperature 300 K emits thermal energy at a rate of $E$. If its absolute temperature is increased to 600 K, what will be the new rate of thermal energy emission?

Accepted Answer

D) $16E$

Answer

A) $2E$

Answer

B) $4E$

Answer

C) $8E$

Question 13

The wavelength corresponding to maximum spectral emissive power for a black body at 2000 K is $1.5\ \mu m$. What will be the peak wavelength when its temperature is increased to 3000 K?

Accepted Answer

A) $1.0\ \mu m$

Answer

B) $2.25\ \mu m$

Answer

C) $0.75\ \mu m$

Answer

D) $1.25\ \mu m$

Question 14

A body cools from $80^\circ ext{C}$ to $60^\circ ext{C}$ in 5 minutes in surroundings kept at $20^\circ ext{C}$. Using Newton's Law of Cooling, how long will it take to cool from $60^\circ ext{C}$ to $40^\circ ext{C}$ in the same surroundings?

Accepted Answer

C) $8 minutes 20 seconds$

Answer

A) 5 minutes

Answer

B) 6 minutes

Answer

D) 10 minutes

Question 15

At what temperature does pure water exhibit its maximum density at standard atmospheric pressure?

Accepted Answer

B) $4^\circ	ext{C}$

Answer

A) $0^\circ	ext{C}$

Answer

C) $100^\circ	ext{C}$

Answer

D) $-4^\circ	ext{C}$

Question 16

If a liquid of coefficient of real cubical expansion $\gamma_r$ is contained in a vessel of coefficient of cubical expansion $\gamma_v$, what is the coefficient of apparent expansion $\gamma_a$ of the liquid?

Accepted Answer

A) $\gamma_a = \gamma_r - \gamma_v$

Answer

B) $\gamma_a = \gamma_r + \gamma_v$

Answer

C) $\gamma_a = \frac{\gamma_r}{\gamma_v}$

Answer

D) $\gamma_a = \gamma_v - \gamma_r$

Question 17

According to Kirchhoff's Law of thermal radiation, what is the ratio of emissive power ($E$) to absorptive power ($a$) for any body in thermal equilibrium?

Accepted Answer

A) Equal to the emissive power of a perfectly black body at the same temperature

Answer

B) Equal to 1.0 for all physical surfaces

Answer

C) Inversely proportional to the absolute temperature

Answer

D) Equal to zero

Question 18

What is the ratio of specific heat capacities $\gamma = C_p / C_v$ for an ideal monatomic gas?

Accepted Answer

C) 1.67

Answer

A) 1.33

Answer

B) 1.40

Answer

D) 1.25

Question 19

A spherical black body of radius 10 cm at 500 K is suspended in an evacuated enclosure maintained at 300 K. Calculate the net rate of heat loss by radiation. (Use $\sigma = 5.67 imes 10^{-8} ext{ W/(m}^2\cdot ext{K}^4)$, $\pi \approx 3.14$)

Accepted Answer

A) 387.4 W

Answer

B) 445.2 W

Answer

C) 210.6 W

Answer

D) 512.8 W

Question 20

Two cylindrical metallic rods A and B are made of the same material. Rod A has half the length and twice the radius of Rod B. Both rods experience the same temperature difference across their ends.

What is the ratio of the rate of heat conduction in Rod A to that in Rod B ($H_A : H_B$)?

Accepted Answer

C) $8 : 1$

Answer

A) $1 : 1$

Answer

B) $4 : 1$

Answer

D) $16 : 1$

Set 7Grade 11 : Physics - Thermal Properties