Questions
When you heat the water in a pot, it boils. What do you infer from above observation?
- Heat is a form of energy
- Water can boil itself
- Water develops heat on its own
- None of the above
When we push a huge block, our body becomes
- Hot
- Cold
- Charged
- Smaller
Heat, as a form of energy, flows from
- a body of higher heat content to that of a lower heat content
- a body of lower heat content to that of a higher heat content
- a hot body to a cold body
- a cold body to a hot body
Amount of heat energy present is determined by :
- Sum total of kinetic energy and the potential energy of its molecules
- Sum total of mechanical energy and surface energy of its molecules
- Sum total of chemical energy and potential energy of its molecules
- All
Form of energy which causes in us sensation of hotness or coldness :
- Surface energy
- Heat energy
- Kinetic energy
- Potential energy
Heat is a from of ______
- Energy
- Work
- Power
- None of these
When heat energy is given out by a hot substance then the kinetic energy of its molecules _________. Fill in the blank.
- Increases
- Decreases
- Remain same
- None
Greater the heat energy, ________ the body. Fill in the blank.
- Hotter
- Colder
- Neutral
- None
Which of the following is false for heat?
- It is a form of energy.
- It cannot be seen but only can be felt.
- If a body's temperature is increased, it gains heat energy.
- It is always produced from chemical energy.
At the molecular level what can be said about Heat energy?
- Heat energy is equal to total mechanical energy of all its molecules
- Heat energy is equal to total potential energy of all its molecules
- Heat energy is equal to total kinetic energy of all its molecules
- Heat energy is equal to total heat energy of all its molecules
Select the option which describes the best definition of heat in the context of thermal energy?
- energy possessed by a system due to movement of particles within the system
- the measure of thermal energy
- thermal energy transferred from one object to another
- energy possessed by an object due to the temperature of the object
- potential energy
The mode of exchange of energy due to temperature difference is known as:
- heat energy
- electric energy
- potential energy
- kinetic energy
The temperature inside a refrigerator is $t _2$ $^0C$ and the room temperature is $t _1$ $^0C$. The amount of heat delivered to the room for each joule of electrical energy consumed ideally will be
- $\frac{t _1}{t _1 - t _2}$
- $\frac{t _1 + 273}{t _1 - t _2}$
- $\frac{t _2 + 273}{t _1 + t _2}$
- $\frac{t _1 + t _2}{t _1 + 273}$
How much heat energy is gained when 5kg of water at $20^{ _-^0}C$ I brought to its boiling point? (Specific heat of water = 4.2 kJ $kg^{-1} C^{-1}$) -
- 1680 kJ
- 1700 kJ
- 1720 kJ
- 1740 kJ
How much heat energy in joules must be supplied to $14\ gms$ of nitrogen at room temperature to rise its temperature by $ 40^o C $ at constant pressure?
(Mol.wt.of $ N _2 = 28 gm , R = constant $)
- $50R$
- $60R$
- $70R$
- $80R$
Confined particles energy is given by
- $\dfrac{{{n^2}{h^2}}}{{2m{L^2}}}$
- $\dfrac{{2{n^2}{h^2}}}{{m{L^2}}}$
- $\dfrac{{{n^2}{h^2}}}{{8m{L^2}}}$
- $\dfrac{{{n^2}{h^2}}}{{4m{L^2}}}$
At $3{ 0 }^{ \circ }C$, a lead bullet of $50\ g$, is fired vertically upwards with a speed of $840\ m/s$. The specific heat of lead is $0.02\ cal/{ g }^{ \circ }C$. on returning to the starting level, it strikes to a cake of ice at $0^{ \circ }C$. Calculate the amount of ice melted (Assume all the energy is spent in melting only)
- $62.7\ g$
- $55\ kg$
- $52.875\ kg$
- $52.875\ g$
A refrigerator has to transfer an average of $263J$ of heat per second from the temperature $-10^oC$ to $25^oC.$ The average power consumed, if no energy is lost is
- $100W$
- $7.5W$
- $25W$
- $35W$
Hailstone at $0^{o}C$ falls from a height of $1\ km$ on an insulating surface converting whole of its kinetic energy into heat. What part of it will melt ? $(g=10\ m/s^{2}$)
- $\dfrac{1}{33}$
- $\dfrac{1}{8}$
- $\dfrac{1}{33}\times 10^{-4}$
- All of it will melt
A block of mass $100\ g$ slides on a rough horizontal surface. If the speed of the block decreases from $10\ m/s^{-1}$ to $5\ m/s^{-1}$, the thermal energy developed in the process is:
- $3.75\ J$
- $37.5\ J$
- $0.375\ J$
- $0.75\ J$
Define the term heat :
- the condition or quality of being hot
- the sensation of warmth or hotness
- the degree of hotness; temperature
- all of the above
Two blocks of steel A and B of the same shape and size, A being two times heavier than B, are at $40^{\circ}C$. The ratio of heat content of A to B is
- $1$
- $4$
- $2$
- $\displaystyle\frac{1}{2}$
State whether given statement is True or False
Heat is an invisible form of energy, which causes the sensation of hotness or coldness.
- True
- False
According to law of conservation of energy, heat energy is transformed into which two types of energy?
- Kinetic and potential energy
- Mechanical and potential energy
- Kinetic and thermal energy
- Nuclear and potential energy