Physics

Thermal Properties and Thermodynamics

380 Questions

Thermal properties and thermodynamics questions evaluate concepts of heat transfer, thermal efficiency, and temperature variations. Problems involve calculating heat content, conductivity, and the performance of heat engines. This subject is regularly tested in physics sections across multiple competitive platforms.

Heat transfer calculationsThermal efficiencyBlack body radiationTemperature variationsRefrigeration performance

Thermal Properties and Thermodynamics Questions

Multiple choice physics solar equipment production of electricity from solar energy solar power alternate sources of energy solar power plant solar energy and its applications renewable and non-renewable resources renewable and non-renewable sources of energy generation of electricity

The temperature in a spherical reflector type solar cooker is raised to above $500 ^oC$ by :

  1. concentrating energy at one point by using a concave reflector

  2. proper insulation of the cooker

  3. concentrating energy at one point by using a convex reflector

  4. Both (A) and (B)
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

A spherical reflector (concave mirror) concentrates solar rays to a single focal point, significantly increasing the temperature. Proper insulation of the cooker is also essential to minimize heat loss to the surroundings, allowing the temperature to reach high levels.

Multiple choice physics solar equipment solar power plant production of electricity from solar energy solar power solar energy and its applications generation of electricity

The room heater can maintain only ${16^0}C$ in the room when the temperature outside is -${20^0}C$. It is not warm and comfortable, that is why the electric stove with power of 1 kw is also plugged in.Together these two devices maintain the room temperature of ${22^0}C$. Determine the thermal  power of the heater.

  1. 3kW

  2. 4 kW

  3. 5kW

  4. 6kW
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The heater maintains a 36-degree difference (16 - (-20)). Adding a 1kW stove increases the temperature by 6 degrees (22 - 16). Since 1kW provides 6 degrees of heating, the heater (which provides 36 degrees) must be 6 times more powerful, but the calculation based on the provided values suggests 5kW.

Multiple choice physics heat and energy causes of greenhouse effect global warming adaptation in animals

A metal ball kept in a cooling room, cools from $72^oC$ to $60^oC$ in $10 $ minutes; and to $52^oC$ in next $10$ minutes. Calculate the temperature of the cooling room

  1. $35^oC$
  2. $38^oC$
  3. $39^oC$
  4. $36^oC$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using Newton's Law of Cooling, the rate of cooling is proportional to the temperature difference between the object and the surroundings. By setting up two equations for the two intervals, the room temperature can be calculated as 36 degrees Celsius.

Multiple choice commercial applications management of natural resources unequal distribution of resources protecting our environment rules are for everyone

According to the Stefan-Boltzmann law, the radiative energy emitted by one square meter of an object is equal to a constant multiplied by its temperature raised to the ____________ power.

  1. Negative third

  2. Zeroeth

  3. Fourth

  4. Tenth
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The Stefan-Boltzmann law states that the power radiated per unit area of a black body is directly proportional to the fourth power of its absolute temperature (P = sigma * T^4).

Multiple choice zoology meaning of life energy flow and loss energy flow in a food chain energy flows

Two objects, A and B, have the same mass but the specific heat of A is larger than B. If both objects absorb equal amounts of energy,

  1. A will become warmer than B

  2. B will become warmer than A

  3. Both A and B will warm at the same rate

  4. A will get warmer, but B will get colder
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The formula for heat absorption is Q = mc * deltaT. Since Q and m are the same for both, deltaT = Q / (mc). If the specific heat c is larger for A, the temperature change deltaT will be smaller for A. Therefore, B will become warmer than A.

Multiple choice physics pressure in fluids and atmospheric pressure pressure in air introduction to atmospheric pressure pressure exerted by air devices to measure pressure

A boiler is made of a copper plate 2.4mm thick with an inside coating of a 0.2mm thick layer of tin.The surface area exposed to gases at ${\rm{70}}{{\rm{0}}^{\rm{0}}}{\rm{C is 400c}}{{\rm{m}}^{\rm{2}}}$ . The amount of steam that could be generated per hour at atmospheric pressure is  ${\rm{(}}{{\rm{K}} _{{\rm{cu}}}}{\rm{ = 0}}{\rm{.9 and }}{{\rm{K}} _{{\rm{tin}}}}{\rm{ = 0}}{\rm{.15cal/cm/s}}{{\rm{/}}^{\rm{0}}}{\rm{C and }}{{\rm{L}} _{{\rm{steam}}}}{\rm{ = 540cal/g)}}$

  1. 5000kg

  2. 1000kg

  3. 4000kg

  4. 200kg
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Heat transfer Q = (T1 - T2) / (d1/k1 + d2/k2) * Area * time. Using the provided thermal conductivities and thicknesses, one calculates the heat flow rate, then divides by the latent heat of steam (540 cal/g) to find the mass generated.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

a piece of lead falls from a height of $100m$ on a fixed non-conducting slab which brings it to rest. If the specific heat of lead is $30.6{\rm{ }}cal/kg{\,^ \circ }C,$, the increase in temperature of the slab immediately after collision is 

  1. ${6.72^ \circ }C$
  2. ${7.62^ \circ }C$
  3. ${5.62^ \circ }C$
  4. ${8.72^ \circ }C$
Reveal answer Fill a bubble to check yourself
D Correct answer
Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

If the amount of heat given to a system is $35\, J$ and the amount of work done on the system is $15\, J$, then the change in internal energy of the system is

  1. $- 50\, J$
  2. $20\, J$
  3. $30\, J$
  4. $50\, J$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Given,

$\Delta Q=+35J$
$\Delta W=-15J$
$\Delta U=?$
From law of thermodynamic,
$\Delta Q=\Delta U+\Delta W$
$\Delta U=\Delta Q-\Delta W$
$\Delta U=35-(-15)$
$\Delta U=35+15$
$\Delta U=50J$
The correct option is D. 

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

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

  1. $15.75g$
  2. $4 g$
  3. $0.3 g$
  4. $0.16 g$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Heat required = mass * specific heat * delta T = 3000 g * 1 cal/g C * 50 C = 150,000 cal = 630,000 J. Fuel consumption rate = Total heat / Heat of combustion = 630,000 J / 40,000 J/g = 15.75 g.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

A hammer of mass 1$\mathrm { kg }$ having speed of 50$\mathrm { m } / \mathrm { s }$ , hit a iron nail of mass 200$\mathrm { gm }$ . If specific heat of iron is 0.105 cal/gm'C and half the energy is converted into heat, the raise in temperature of nail is

  1. $7.1 ^ { \circ } C$
  2. $9.2 ^ { \circ } \mathrm { C }$
  3. $10.5 ^ { \circ } C$
  4. $12.1 ^ { \circ } \mathrm { C }$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Initial kinetic energy = 0.5 * m * v^2 = 0.5 * 1 * 50^2 = 1250 J. Half of this is 625 J. Convert to calories: 625 / 4.2 = 148.8 cal. Heat = ms(delta T) -> 148.8 = 200 g * 0.105 cal/g C * delta T. delta T = 148.8 / 21 = 7.08 C.

Multiple choice physics the essence of change different forms of energy energy conversions energy transformations and energy transfers

Work done by 100 calorie of heat is __________.

  1. 418.4 J

  2. 4.184 J

  3. 41.84 J

  4. None of these
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation
For an isothermal expansion of an ideal gas, the change in internal energy is zero.

According to the first law of thermodynamics, 

Change in internal energy U = Q-W = 0

So, all the heat energy is utilized to do work. 

Q = W

We know that, one calorie is equal to 4.184 J

Therefore, Work done by 100 calorie of heat in an isothermal expansion of any ideal gas will be 4.184 * 100 =  418.4 Joule