8th Class Science Friction Question Bank

Fill in the blanks. (a) Friction opposes the _____ between the surfaces in contact with each other. (b) Friction depends on the ______ of surfaces. (c) Friction produces.______. (d) Sprinkling of powder on the carrom board _____ friction. (e) Sliding friction is _____ than the static friction. (f) The force of friction always ____ the motion of an object. (g) Friction _____when you press the two surfaces hard together. (h) The smoother a surface is, the____ will be the friction. (i) Rolling friction is____ than sliding friction. (j) The soles of our shoes wear out-in a few months due to____ (k)  ____is a self-adjusting force. (l) The force of friction which does not allow one body to slide upon another is called____ (m) Frictional force in a ceiling fan is reduced by using_____ (n) Aeroplanes are streamlined to reduce____ friction. (o) With increase of temperature, the frictional force acting between two surfaces ____ (p) We can not walk on ice or on a very smooth surfaces because friction between our shoes and these   surfaces is ____ (q) The bodies of aeroplanes, missiles, rockets, cars are streamlined to reduce friction with air, called (r) The frictional force that fluids exert on object is called_____ (s) To reduce fluid friction, the shape of object should have a____ (t) Friction can be ____or ____by adopting proper methods. (u) Lubricants are used to ____friction. (v) The friction offered by wheels is called (w) Ball bearings converts the sliding friction to (x) Friction prevents movement until the force applied is____ than the force of friction. (y) Friction is a ____ force.

Suppose your writing desk is tilted a little. A book kept on it starts sliding down. Show the direction of frictional force acting on it.

You spill a bucket of soapy water on a marble floor accidentally. Would it make it easier or more difficult for you to walk on the floor? Why?

Explain why sportsmen use shoes with spikes.

Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

Explain why sliding friction is less than static friction.

Give examples to show that friction is both a friend and a foe.

Explain why objects moving in fluids must have special shapes.