CLASS 8 REVISION FRICTION

FRICTION

CLASS 8

REVISION

1.To sharpen the blade of a knife by rubbing it against a surface,
which of the following will be most suitable?
(a) stone (c) wooden block
(b) plastic block (d) glass block
2. A toy car released with the same initial speed will travel
farthest on
(a) muddy surface (c) cemented surface

(b) polished marble surface (d) brick surface
3.If we apply oil on door hinges, the friction will
(a) increase (c) disappear altogether

(b) decrease (d) will remain unchanged
4.Two blocks of iron of different masses are kept on a cemented
floor . Which one of them would require a

larger force to move it from the rest position?

5.Two boys are riding their bicycles on the same concrete road.
One has new tyres on his bicycle while the other has tyres that
are old and used. Which of them is more likely to skid while
moving through a patch of the road which has lubricating oil

spilled over it?

6.You might have noticed that when used for a long time, slippers

with rubber soles become slippery. Explain the reason.
7.We have two identical metal sheets. One of them is rubbed with
sand paper and the other with ordinary paper. The one rubbed

with sand paper shines more than the other. Give reason.