Friction

Friction is a

• non-contact force

• contact force

• magnetic force

• electrostatic force

Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play

• only if the objects are solid

• only if one of the two objects is liquid

• only if one of the two objects is gaseous

• irrespective of whether the objects are solids, liquids or gases

Two blocks of iron of different masses are kept on a cemented floor as shown in the figure. Which one of them would require a larger force to move it from the rest position? Block 1 or Block 2 ?

Which of the following produces least friction?

• Sliding friction

• Rolling friction

• Composite friction

• Static friction

Friction always

• (a) opposes the motion

• (b) helps the motion

• (c) both (a) and (b)

• (d) none of these

Friction can be reduced by using

• oil

• grease

• powder

• all of these

Static friction is less than

• (a) sliding friction

• (b) rolling friction

• (c) both (a) and (b)

• (d) none of these

The shape of an aeroplane is like a

• Dog

• Bird

• Car

• All of These

Friction is

• (a) Foe

• (b) Friend

• (c) A necessary

• (d) All of These

Friction due to fluids is called

• force

• pressure

• friction

• drag