The force that acts between the object and the surface is called _________________.

• magnetic force

• gravitational force

• force of friction

Substances that can reduce friction are called _____________.

• engines

• lubricants

• muscles

This surface offers less force of friction.

• smooth surface

• rough surface

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Friction between paper and pencil helps us to __________.

• sing

• dance

• write

• sleep

Rubbing of two surfaces generates heat.

• True

• False

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How can we reduce friction?

• By oiling

• Using powder

• Using grease and wax

• All of these

In which direction does frictional force act on a moving object?

• same direction

• opposite direction

• in the centre

Which one of these shows frictional force?

• Leaf falling to the ground

• Man pushing a trolley

• Child sleeping on a bed

Somu is playing with his toy truck. On which surface will his truck move the slowest?

• smooth surface

• rough surface

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The harmful effects of friction are ___________.

• Wear and tear of moving parts

• Unwanted heat is produced

• Both of these