Tag: heat energy transfers

Quizzes (5) Questions (137)

Questions Related to heat energy transfers

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

State whether given statement is True or False
To prevent heat conduction to our hands, handle of cooking vessels are made of bad conductors.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Good conductor will transfer the heat from vessel's handle to our hands and let our hands burn. So, bad conductor of heat, materials is used for manufacturing of vessel's handle.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

What type of conductor should we used to make water pipes in cold countries?

  1. Good conductor

  2. Poor conductor or bad conductor

  3. Material does not help in such cases

  4. None of the above
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Poor conductor should be used, so that they will not allow heat to pass from water inside the pipe to outside atmosphere to prevent water from freezing. It will help pipes from busting.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

On a cold day when a room temperature is $15^oC$, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of $15^oC$, because

  1. metals have higher thermal capacity than plastics

  2. plastics have a lower density than metals

  3. metals are good conductor of heat

  4. plastics have a higher thermal conductivity than metals
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

On a cold day when a room temperature is $15^oC$, the metallic cap of a pen becomes much colder than its plastic body, though both are at the same temperature of $15^oC$ because metals are good conductor of heat, so they could absorb and release heat in a better way than insulators.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Two thin walled sphere of different materials ,one with double the radius and one fourth wall thickness of the other are filled with ice If the time taken for complete melting of ice in the sphere of larger radius is $25$ minutes and that for smaller one is $16$ minutes,the ratio of thermal conductivities of the materials of larger sphere to the smaller sphere is  

  1. $4:5$

  2. $25:1$

  3. $1:25$

  4. $8:25$
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Using the heat conduction formula Q = (KA dT t) / d, where Q is proportional to mass (volume * density), we relate the time taken to melt ice to the thermal conductivity. The ratio of conductivities is derived from the given radii, thicknesses, and times.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Iron, lead and brass spheres of equal masses are heated to a common temperature and are kept on a sheet of wax. The sphere that passes through the plate first is (lead 0.03 $\operatorname { cal } / \mathrm { g } / ^ { \circ } \mathrm { C }$, iron 0.11 $\operatorname { cal } / \mathrm { g } / ^ { \circ } \mathrm { C }$, brass 0.08 $\operatorname { cal } / \mathrm { g } / ^ { \circ } \mathrm { C }$) 

  1. lead

  2. brass

  3. iron

  4. all at the same time
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The rate of heat transfer through the spheres depends on their specific heat capacity. Since they have equal masses and are heated to the same temperature, the one with the lowest specific heat capacity will transfer heat the fastest to the wax, but the question implies they all melt through at the same time if the heat capacity is not the limiting factor or if the setup is idealized.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Glaciers melt:

  1. first at the bootom due to decress in pressure

  2. first at the top due to iuncrease in pressure

  3. first at the bottom due to increase in pressure

  4. first at the top due to increase in pressure
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The melting point of ice decreases with an increase in pressure. The weight of the glacier creates higher pressure at the bottom, causing the ice to melt there first.

Multiple choice physics heat energy transfers heat and heat transfer heat energy transfer transfer of heat

Two rods having thermal conductivities in the ratio of 5:3 and having equal length length and equal cross-section are joined by face to face. If the temperature of free end of first rod is $100^oC$ and temperature of  free end of second rod is $20^oc$, then temperature of the junction, is-

  1. $90^oC$

  2. $85^oC$

  3. $70^oC$

  4. $50^oC$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Let the thermal conductivity of first rod be $5 K$

Let the thermal conductivity of second rod be $3 k$
now, sum of heat current flowing through the junction =0
$\begin{array}{l} \frac { { 5KA\left( { 100-T } \right)  } }{ x } +\frac { { 3KA\left( { 20-T } \right)  } }{ x } =0 \ 500-5T+60-3T=0 \ 8T=560 \ \therefore T={ 70^{ 0 } }C \end{array}$