Question of Exercise 1

Friction of Class 8

A force that opposes the motion of one surface sliding over another is called :


Option 1 lubrication

Option 2 ball bearing

Option 3 friction

Option 4 polishing

Frequently Asked Questions

What is a Kaleidoscope

A: A cylinder with mirrors containing loose colored objects such as beads, pebbles, and bits of glass

B: A cylinder with mirrors

C: A cylinder containing loose colored objects such as beads, pebbles, and bits of glass

D: None of the above



A kaleidoscope is a cylinder instrument consisting of mirrors and loose-colored objects such as beads, pebbles, and bits of glass. The viewer can see the colorful patterns created when the end of the kaleidoscope is lightened due to repeated reflections formed by the mirrors.

Final Answer:

Hence, option A is correct.


1 pascal is equal to ..Nm^-2



Pascal is the unit of pressure. Pressure is the force applies on unit area. Therefore, 

1 pascal =1 Nm-2

Final Answer:

Hence,1 pascal is equal to 1 Nm-2.


Which object is vibrating when the following sounds

are produced?a) the sound of a sitar b) the sound of a table c) the sound of a tuning fork d) the buzzing of a bee or mosquito e) the sound of a flute?




When a vibrating tuning fork is placed on a table, then a large sound is heard because  the entire system begins vibrating and forces surrounding air particles into vibration motion.

The tendency of one object to force another adjoining or interconnected object into vibration motion is referred to as a forced vibration.

Final Answer: 

Therefore, option B is correct.


Differentiate between luminous and non uminous objects



The differences between luminous and non-luminous objects are,

Luminous Objects Non-luminous Objects

Luminous objects are objects that can emit

light energy on theirown.

Non-luminous things are those that cannot

emit light energyon their own.

These things can produce a light sense. These things do not produce a bright sense.

Because they emit light on their own,

the bright objects are visible.

Because of the bright things, non-luminous

objects are seen.

Two examples are the sun and the candle. Two examples are the moon and planets.

Final answer:

Hence, the differences between luminous and non-luminous objects are tabulated above.

Lightning occurs because of

A: rain

B: electric discharge

C: wind

D: shaking of earth




Lightning is a natural discharge of the static built up in the clouds during a storm.

This effect occurs due to the separation of the positive and negative ions during a storm.

Final Answer:

Hence, option B is correct.


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