Heat

IMPORTANT

Heat: Overview

This Topic covers sub-topics such as Temperature, Heat, Heat Transfer, Specific Heat Capacity, Heat Capacity, Kelvin Scale, Celsius Scale, Relation between Temperature Scales and, Reaction between Zinc and Copper Sulphate

Important Questions on Heat

MEDIUM
IMPORTANT

Specific heat capacity is defined as the amount of heat required to raise the temperature of a substance by 1 K or 1°C.

HARD
IMPORTANT

To what temperature in °C will 250 g of mercury rise from an initial temperature of 10 °C, if 5.425×103 joules of heat energy is transferred into the system? The specific heat capacity of mercury is 140 J kg-1 K-1.

HARD
IMPORTANT

A 20 g piece of iron absorbs 1251.2 J of heat energy and its temperature changes from 25 °C to 161 °C. Calculate the specific heat capacity of iron.

EASY
IMPORTANT

The temperature of a 4.0 g block of pure aluminium increases from 25 oC to 45 oC. If the specific heat capacity of aluminium is 900 J kg-1 K-1, calculate the amount of energy required in joules for this temperature increase.

HARD
IMPORTANT

It takes 2,100 J to heat 500 gm of water by 1 K (or by 1 oC). How much energy does it take to raise the temperature of 2 kg of copper by 0.5 K?

Substance Specific heat capacity c J kg-1 K-1
Water  4,200
Copper 390

MEDIUM
IMPORTANT

Convert 33 °C  to kelvin to nearest integer.

MEDIUM
IMPORTANT

Convert -48 °C  to kelvin to nearest integer.

EASY
IMPORTANT

The temperature of a steel rod is 330 K. Its temperature in °C is _____.

EASY
IMPORTANT

In the given diagram, the possible direction of heat energy transformation is
Question Image

MEDIUM
IMPORTANT

Two spheres of the same material have radii 1 m and 4 m and temperatures 4000 K and 2000 K respectively. Find ratio of the energy radiated per second by the first sphere to that by the second is.

EASY
IMPORTANT

Write the unit in words for the following symbol: °C.

MEDIUM
IMPORTANT

Heat always travels from cooler area to the warmer one.

EASY
IMPORTANT

In Fahrenheit scale, the lowest fixed point is taken as _____0F.

HARD
IMPORTANT

The rate of heat loss at $t=600$ sec after the heater is switched off (as in table- 2) is

HARD
IMPORTANT

By varying the voltage applied to the kettle, you can change power consumption P. Depending on the P of kettle, water can be heated to different maximum temperatures. This dependence is shown in table.

  Table      
Power Pin Watt 0 100 200 300
Temperature Tin °C 20 40 60 80

If the power consumption is 400 W

EASY
IMPORTANT

Write the symbol for the following unit: Degree Celsius

EASY
IMPORTANT

A steel drill making 180rpm is used to drill a hole in a block of steel. The mass of steel block and the drill is 180gm each. The entire mechanical work is used up in producing heat such that the rate of rise of temperature of the system is 0.5°C/sec. If τ is the couple required to drive the drill then, find its value in SI units.
(Csteel=0.10cal/gm°C,J=4.186)

EASY
IMPORTANT

A certain bullet of mass 6gm melts at 300oC and has specific heat as 0.20Kcal/kg and a heat fusion of 15kcalkg. The heat needed to melt the bullet if it was originally at 0oC, can be written as λkJ. Then the value of λ is. J=4

EASY
IMPORTANT

Specific heat of a substance varies with absolute temperature as s =B T2 J/kgK where
B=3Jkg-K3 The amount of heat required to raise the temperature of 3 kg substance from 0 K to 10 K can be written as λ×10n J. Find the value of λ, where λ and n are integers.

EASY
IMPORTANT

A cube of iron (density =8000 kg/m3, siron=470 J/kgK) is heated to a high temperature and is placed on a large block of ice at 0oC. The cube melts the ice below it, displaces the water and sinks. In the final equilibrium position, its upper surface just goes inside the ice. If the initial temperature of block is 10λ then find the value of λdice=900 kg/m3, Lf=3.34×105 J/kg.