Friction Class 8 MCQs Questions with Answers
I. Choose the correct option.
Question 1.
Friction is a
(a) non-contact force
(b) contact force
(c) magnetic force
(d) electrostatic force
Answer
Answer: (b) contact force
Question 2,.
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 3.
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 4.
Friction can be reduced by using
(a) oil
(b) grease
(c) powder
(d) all of these
Answer
Answer: (d) all of these
Question 5.
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 6.
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 7.
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 8.
The shape of an aeroplane is like a
(a) dog
(b) bird
(c) car
(d) all of these
Answer
Answer: (b) bird
Question 9.
Friction is
(a) foe
(b) friend
(c) both (a) and (b)
(d) none of these
Answer
Answer: (c) both (a) and (b)
Question 10.
Friction due to fluids is called
(a) force
(b) pressure
(c) friction
(d) drag
Answer
Answer: (d) drag
Question 11.
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 12.
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 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
II. Fill in the Blanks
Question 1.
Sliding friction is __________ than static friction.
Answer
Answer: less
Question 2.
Friction can be reduced by using__________
Answer
Answer: oil or powder or grease
Question 3.
Friction can be increased by making surface__________
Answer
Answer: rough
Question 4.
Rolling friction is __________ than sliding and static friction.
Answer
Answer: less
Question 5.
Friction due to fluid is also called __________
Answer
Answer: drag
Question 6.
Bodies of birds, fishes and ships are __________
Answer
Answer: streamlined
Question 7.
Friction can also produce __________
Answer
Answer: heat
Question 8.
All objects moving in fluids have __________ shape to reduce __________
Answer
Answer: streamlined, friction
Question 9.
Rough surfaces produce __________ friction than smooth surfaces.
Answer
Answer: more
Question 10.
In many machines, friction is reduced by using __________
Answer
Answer: ball bearing
Question 11.
Friction depends on the __________ of substances in contact.
Answer
Answer: nature
Question 12.
Static friction comes into play when we try to move an object at __________
Answer
Answer: rest
Question 13.
__________ force is responsible for downward movement of a parachutist when he jumps from an air-craft
Answer
Answer: Gravitational
Question 14.
The sole of shoes and the tyres of vehicles are treaded to __________ friction.
Answer
Answer: increase
Question 15.
Friction is sometimes ___________
Answer
Answer: undesirable
III. True or False
Question 1.
Friction is always useful to us.
Answer
Answer: False
Question 2.
Fluids are only liquids.
Answer
Answer: False
Question 3.
Friction is less for smooth surfaces.
Answer
Answer: True
Question 4.
A soapy floor is slippery due to increased friction.
Answer
Answer: False
Question 5.
Friction always works in opposite direction to the relative motion.
Answer
Answer: True
Question 6.
Friction is dependent on area of contact.
Answer
Answer: False
Question 7.
Sliding friction is less than rolling friction.
Answer
Answer: False
Question 8.
Friction decreases with increase in the smoothness of the surface.
Answer
Answer: True
Question 9.
It is easier to move a heavy object than a light object.
Answer
Answer: False
Question 10.
Friction can be reduced by using lubricants.
Answer
Answer: True
Question 11.
Friction is independent of the nature of surfaces in contact.
Answer
Answer: False
Question 12.
A spring balance measures force.
Answer
Answer: True
Question 13.
Friction can be reduced by using ball bearings in some machines.
Answer
Answer: True
Question 14.
Friction can never be eliminated.
Answer
Answer: True
Question 15.
Friction do not produce heat.
Answer
Answer: False
IV. Match the following
| Column I | Column II |
| 1. Fluid friction | (a) Due to friction |
| 2. Lubricants | (b) Streamlined |
| 3. Wheels | (c) Increases friction |
| 4. Spring balance | (d) Drag |
| 5. Shape of aeroplane | (e) Rolling friction |
| 6. Rough surface | (f) Reduce friction |
| 7. Heat generation | (g) Measures force |
Answer
Answer:
| Column I | Column II |
| 1. Fluid friction | (d) Drag |
| 2. Lubricants | (f) Reduce friction |
| 3. Wheels | (e) Rolling friction |
| 4. Spring balance | (g) Measures force |
| 5. Shape of aeroplane | (b) Streamlined |
| 6. Rough surface | (c) Increases friction |
| 7. Heat generation | (a) Due to friction |
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