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## Wednesday, 24 February 2021

### CBSE Class 8 Science - MCQ and Online Tests - Unit 12 - Friction

#### CBSE Class 8 Science – MCQ and Online Tests –  Unit 12 – Friction

Every year CBSE students attend Annual Assessment exams for 6,7,8,9,11th standards. These exams are very competitive to all the students. So our website provides online tests for all the 6,7,8,9,11th standards’ subjects. These tests are also very effective and useful for those who preparing for any competitive exams like Olympiad etc. It can boost their preparation level and confidence level by attempting these chapter wise online tests.

These online tests are based on latest CBSE syllabus. While attempting these, our students can identify their weak lessons and continuously practice those lessons for attaining high marks. It also helps to revise the NCERT textbooks thoroughly

#### 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

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

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

Question 4.
Static friction is less than
(a) sliding friction
(b) rolling friction
(c) both (a) and (b)
(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: (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

Question 7.
The shape of an aeroplane is like a
(a) dog
(b) bird
(c) car
(d) all of these

Question 8.
Friction is
(a) foe
(b) friend
(c) both (a) and (b)
(d) none of these

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: (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: (a) Wearing out due to friction

Question 11.
Friction is a
(a) non-contact force
(b) contact force
(c) magnetic force
(d) electrostatic force

Question 12.
Which of the following produces least friction?
(a) Sliding friction
(b) Rolling friction
(c) Composite friction
(d) Static friction

Question 13.
If we apply oil on door hinges, the friction will
(a) increase
(b) decrease
(c) disappear altogether
(d) will remain unchanged

Question 14.
Lubricant
(a) reduce friction
(b) increase friction
(c) both (a) and (b)
(d) none of these

Question 15.
Force of friction depends on
(a) roughness of surface
(b) smoothness of surface
(c) inclination of surface
(d) all of these

Question 16.
Force of friction depends on
(a) roughness of surface
(b) weight
(c) size
(d) all of these

Question 17.
Fluids are
(a) liquids
(b) gases
(c) both (a) and (b)
(d) none of these

Answer: (c) both (a) and (b)

Question 18.
Which is a streamlined object?
(a) Boats
(b) Aeroplanes
(c) Ships
(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

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

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: (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

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: (a) Friction may cause fire

Question 24.
(a) look good
(b) Increase friction
(c) increase its longivity
(d) increase weight of the tyre

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

Question 26.
Sliding friction is _________ than / to rolling friction
(a) smaller
(b) greater
(c) equal
(d) None of the above

Question 27.
The frictional force exerted by fluids is also called ______
(a) drug
(b) drag
(c) drop
(d) drown

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

Question 29.
Friction always
(a) opposes the motion
(b) helps the motion
(c) both (a) and (b)
(d) none of these

Question 30 .
Friction can be reduced by using
(a) oil
(b) grease
(c) powder
(d) all of these

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