CLASS VII
WORKSHEET (HEAT AND TEMPERATURE)

I. Look at the fig. and explain the three modes of heat transfer.
II Fill in the blanks-

1.Solids ____________ on heating and ____________ on cooling.

2.Among matter _________ expands the most and _______ the least.

3.Two bodies are said to be in the state of thermal ____________ if

there is no transfer of heat taking place.

4.Liquids and gases are generally ____________ conductors of heat.

5.Ocean current are caused by the setting up of __________ in water.

6.During night time cool breeze blows from _________ to ________.

7.____________ and ____________ are good conductors of heat.

8.Transfer of heat takes place from a body at __________ temperature

to a body at ____________ temperature.

9.Transfer of heat may take place by either ___________, _________

or ____________.

10.Black surfaces are better __________ of heat than polished surfaces.

11.Heat is a form of ____________.

12.The fixed temperature at which matter is in a liquid state changes to

its solid state is called ____________.

13.Temperature is a measure of ____________ of a body.

14.Increase in size of the object when heated is called _________.

 15.Thermal expansion is maximum in ____________.

16.Temperature is the degree of ____________ of a body.

17.Heating of metals is through the mechanism of ____________.

18.Heat from the sun reaches us through the mode of ____________.

19.Land and sea breezes are caused by ____________ currents.

III.The statements given below are incorrect. Write the correct

statements.

1.The heat coming from the sun travels by convection.

2.More is the heating, less is the expansion of solids

3.Air conducts heat.

4.People prefer wearing black clothes in summer.

CLASS VIII
WORKSHEET (FRICTION)

I.Fill in the blanks :

1. The force of friction always act in the _____________ direction to the applied force.
2. _____________ comes into play when we try to move an object at rest.
3. _____________ comes into play when an object is sliding over other object.
4. Sliding friction is always _____________ than static friction.
5. Friction can be _____________ by using lubricants.
6. Friction is the force which _____________ the relative motion between two surfaces.
7. Friction can be increased by making a surface _____________.
8. The friction force exerted by fluid is also called _____________.
9. The common name of gases and liquids is _____________.
10. The device used for measuring the force acting on an object _____________.

II. ANSWER THE FOLLOWING QUESTIONS

1.Explain Why, it is easier to drag a mat on floor when nobody is sitting on it but
much more difficult to drag the same mat when a person is sitting on it.
2.Which type of surfaces produce {a} least friction, and {b} too much friction?
3.Out of sliding friction, static friction & rolling friction:
(a) Which one is the smallest?
(b) Which one is the largest?
4. When a pencil cell is released from a certain point on an inclined wooden board, it
travels a distance of 35 cm on floor A before it comes to rest. When the same
pencil cell is released from the same point on the same inclined board, it travels a
distance of 20 cm on floor B before coming to rest. Which floor, A or B, offers
greater friction? Give reason for your answer.
5.A car is moving towards North. What will be the direction of force of friction
acting on this car due to surface of road?

	worksheet-I
Matter in our surroundings		CLASS-IX

.What are the conditions for 'something' to be called matter?  Can matter change its state? State the conditions under which it changes.

. When sugar is dissolved in water , there is no increase in the volume.Which characteristics of matter is illustrated by this observation? .  Why do we see water droplets on the outer surface of a glass containing ice-cold water?

Explain why there is no rise in temperature of water when it starts boiling although it is still being heated.

What is dry ice? Why it is known so?  .Naphthalene balls disappear with time without leaving any solid. Why?  A drop of ink and a drop of honey is placed in water. Which of the two will spread faster-and Why? Ice floats on water. Why?  The boiling point of water is much higher than that of petroleum ether. In which of the two the intermolecular forces are strong?  Explain why a small volume of water in a kettle can fill a kitchen with steam.  Give one example of diffusion of one solid into another solid. Name two gases that which dissolve in water by diffusion .What is the importance of this process in nature? The Kelvin temperature is 270K. What is the corresponding Celsius scale temperature?  Explain two reasons for saying that wood is a solid.