CBSE Class 8 Science – MCQ and Online Tests – Unit 12 – Friction
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CBSE Class 8 Science – MCQ and Online Tests – Unit 12 – Friction
Choose the correct option.
Question 1.
Friction due to fluids is called
(a) force
(b) pressure
(c) friction
(d) drag
Answer
Answer: (d) drag
Question 2.
A toy car released with the same initial speed will travel farthest on
(a) muddy surface
(b) polished marble surface
(c) cemented surface
(d) brick surface
Answer
Answer: (b) polished marble surface
Question 3.
Which of the following is not a smooth surface?
(a) Surface of wet soap
(b) Surface of tyres
(c) Glazed tiles
(d) Surface of mirror
Answer
Answer: (b) Surface of tyres
Question 4.
Static friction is less than
(a) sliding friction
(b) rolling friction
(c) both (a) and (b)
(d) none of these
Answer
Answer: (d) none of these
Question 5.
Whenever the surfaces in contact tend to move or move with respect to each other, the force of friction comes into play
(a) only if the objects are solid.
(b) only if one of the two objects is liquid.
(c) only if one of the two objects is gaseous.
(d) irrespective of whether the objects are solid, liquid or gaseous.
Answer
Answer: (d) irrespective of whether the objects are solid, liquid or gaseous.
Question 6.
To sharpen the blade of a knife by rubbing it against a surface, which of the following will be most suitable?
(a) Stone
(b) Plastic block
(c) Wooden block
(d) Glass block
Answer
Answer: (a) Stone
Question 7.
The shape of an aeroplane is like a
(a) dog
(b) bird
(c) car
(d) all of these
Answer
Answer: (b) bird
Question 8.
Friction is
(a) foe
(b) friend
(c) both (a) and (b)
(d) none of these
Answer
Answer: (c) both (a) and (b)
Question 9.
A boat or an aeroplane has a pointed or tapering front / head. Why?
(a) To increase the friction of fluid
(b) To reduce the friction of fluid
(c) To look good
(d) For no reason
Answer
Answer: (b) To reduce the friction of fluid
Question 10.
The sole of the shoes becomes plain after wearing it for several months. The reason is
(a) Wearing out due to friction
(b) Wearing out due to no friction
(c) Sole is of bad quality
(d) None of the above
Answer
Answer: (a) Wearing out due to friction
Question 11.
Friction is a
(a) non-contact force
(b) contact force
(c) magnetic force
(d) electrostatic force
Answer
Answer: (b) contact force
Question 12.
Which of the following produces least friction?
(a) Sliding friction
(b) Rolling friction
(c) Composite friction
(d) Static friction
Answer
Answer: (b) Rolling friction
Question 13.
If we apply oil on door hinges, the friction will
(a) increase
(b) decrease
(c) disappear altogether
(d) will remain unchanged
Answer
Answer: (b) decrease
Question 14.
Lubricant
(a) reduce friction
(b) increase friction
(c) both (a) and (b)
(d) none of these
Answer
Answer: (a) reduce friction
Question 15.
Force of friction depends on
(a) roughness of surface
(b) smoothness of surface
(c) inclination of surface
(d) all of these
Answer
Answer: (d) all of these
Question 16.
Force of friction depends on
(a) roughness of surface
(b) weight
(c) size
(d) all of these
Answer
Answer: (d) all of these
Question 17.
Fluids are
(a) liquids
(b) gases
(c) both (a) and (b)
(d) none of these
Answer
Answer: (c) both (a) and (b)
Question 18.
Which is a streamlined object?
(a) Boats
(b) Aeroplanes
(c) Ships
(d) All of these
Answer
Answer: (d) All of these
Question 19.
Smooth surface has
(a) less friction
(b) more friction
(c) sometimes less and sometimes more
(d) all of these
Answer
Answer: (a) less friction
Question 20.
Which of the following is responsible for wearing out of bicycle tyres?
(a) Muscular force
(b) Magnetic force
(c) Frictional force
(d) Electrostatic force
Answer
Answer: (c) Frictional force
Question 21.
It is difficult to walk on an oily floor because
(a) Floor gets spoiled
(b) There is more resistance
(c) Force of friction is high
(d) Force of friction is very less
Answer
Answer: (d) Force of friction is very less
Question 22.
Spring balance is a device used for measuring the _____________ acting on an object.
(a) mass
(b) pressure
(c) force
(d) None of the above
Answer
Answer: (c) force
Question 23.
A matchstick struck on a matchbox catches fire easily because
(a) Friction may cause fire
(b) Of chemical reaction
(c) Force heated the match stick
(d) None of the above
Answer
Answer: (a) Friction may cause fire
Question 24.
Tyres are treaded to
(a) look good
(b) Increase friction
(c) increase its longivity
(d) increase weight of the tyre
Answer
Answer: (b) Increase friction
Question 25.
Lubricants are substances which
(a) Increase friction
(b) Are used to light fire
(c) Reduce friction
(d) Are used to put out a fire
Answer
Answer: (c) Reduce friction
Question 26.
Sliding friction is _________ than / to rolling friction
(a) smaller
(b) greater
(c) equal
(d) None of the above
Answer
Answer: (b) greater
Question 27.
The frictional force exerted by fluids is also called ______
(a) drug
(b) drag
(c) drop
(d) drown
Answer
Answer: (b) drag
Question 28.
Four children were asked to arrange forces due to rolling, static and sliding frictions in an increasing order. Their arrangements are given below. Choose the correct arrangement.
(a) Rolling, Static, Sliding
(b) Static, Rolling, Sliding
(c) Rolling, sliding, static
(d) Sliding, Static, Rolling
Answer
Answer: (c) Rolling, sliding, static
Question 29.
Friction always
(a) opposes the motion
(b) helps the motion
(c) both (a) and (b)
(d) none of these
Answer
Answer: (a) opposes the motion
Question 30 .
Friction can be reduced by using
(a) oil
(b) grease
(c) powder
(d) all of these
Answer
Answer: (d) all of these
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