CBSE Questions for Class 8 Physics Friction Quiz 4 - MCQExams.com

State whether the given statement is true or false :
Friction is a necessary evil.
  • True
  • False
Is friction necessary to walk on the moon?
  • Yes
  • No
  • May be
  • Ambiguous
Which of the following best describe friction ?
  • can occur only between two surfaces that are moving relative to one another.
  • is equal to the normal force divided by the magnitude of friction.
  • opposes the relative motion between two surfaces in contact
  • only depends on one of the surfaces in contact.
  • is not equal to the applied force.
Hailstones falling from atmosphere relates to:
  • Static friction
  • Rolling friction
  • Sliding friction
  • Fluid friction
Frictional force is important for motor racing. This is because frictional force.
  • can help a car to slow down
  • can help a car to move faster
  • can help a car move around the corners without skidding
  • none of these
 Fill in the blank.
Fluid Friction is ______ the sliding friction of solids.
  • higher than
  • lower than
  • same as
  • higher than or equal to
The deeper we go inside a flowing river, fluid friction:
  • Decreases
  • Increases
  • Remains same
  • Becomes zero
Which of the following statements indicates advantage of fluid friction?
  • Walking on road
  • Rolling stone on carpet
  • Lubricating machine parts
  • None of the above
Which of the following are done to increase  friction?
  • Making groove in the shoes
  • polishing rough surface
  • using ball bearing in wheels
  • Creating an air cushion
Which of the following factors affects friction ?
  • Nature of the surface
  • Weight of object placed over other
  • Amount of surface area in contact between the moving bodies
  • Both A and B 
Which of the following powders is used as a lubricant to reduce friction in machines ?
  • Graphite
  • Chalk
  • Sand
  • Crushed stone
Why carrom board is usually powdered before playing?
  • For increasing friction.
  • For decreasing friction.
  • For decoration.
  • For fragrance.
Friction can be increased by increasing:
  • Smoothness of the surface
  • Grease on the surface
  • Roughness of the surface
  • Lubricating the surface
Choose the correct option 
  • The friction force is dependent on the roughness of the surface.
  • The kinetic friction is proportional to normal reaction.
  • The friction is independent on the area of contact.
  • All statement are correct.
Does the smoothness of a surface reduce the friction force ?
  • Yes
  • No
  • Sometimes
  • Depend on the amount of force appiled
Fill in the blanks 
Dynamic Fluid friction is _______ the sliding friction of solids.
  • heigher than
  • lower than
  • same as
  • higher than or equal to
Match the following
List IList II
a. frictional forcee. reduction of friction
b. rolling frictionf. causes wear and tear
c. ball bearingg. less than kinetic friction
d. trading of surfaceh. increase of friction 


The correct match is
  • $$a \rightarrow i; b \rightarrow e; c \rightarrow h; d \rightarrow f$$
  • $$a \rightarrow f; b \rightarrow f; c \rightarrow e; d \rightarrow g$$
  • $$a \rightarrow f; b \rightarrow g; c \rightarrow e; d \rightarrow h$$
  • $$a \rightarrow i; b \rightarrow f; c \rightarrow h; d \rightarrow e$$
In fig, a boy is shown pushing the box from right to left. The force of friction will act on the box:

82148_946dd9d8adf44f69922c615798657717.png
  • from right to left $$\left (\leftarrow \right)$$
  • from left to right $$\left (\rightarrow \right)$$
  • vertically downwards $$\left (\downarrow \right)$$
  • vertically upwards $$\left (\uparrow \right)$$
To sharpen the blade of a knife by rubbing it against a surface, which of the following will be most suitable?
  • stone
  • plastic block
  • wooden block
  • glass block
A boy rolls a rubber ball on a wooden surface. The ball travels a short distance before coming to rest. To make the same ball travel longer distance before coming to rest, he may
  • spread a carpet on the wooden surface.
  • cover the ball with a piece of cloth.
  • sprinkle talcum powder on the wooden surface.
  • sprinkle sand on the wooden surface.
Whenever the surfaces in contact, tend to move or move with respect to each other, the force of friction comes into play:
  • only if the objects are solid.
  • only if one of the two objects is liquid.
  • only if one of the two objects is gaseous.
  • irrespective of whether the objects are solid, liquid or gaseous.
A toy car released with the same initial speed will travel farthest on:
  • muddy surface.
  • polished marble surface.
  • cemented surface.
  • brick surface.
Which of the following statements is incorrect?
  • Friction acts on a ball rolling along the ground.
  • Friction acts on a boat moving on water.
  • Friction acts on a bicycle moving on a road.
  • Friction does not act on a ball moving through air.
Two persons, pull each other through a massless rope in 'tug of war' game.  Who will win ?

72349_cf4f0755db6a438aaa9f391850955d2d.png
  • One whose weight is more.
  • One who pulls the rope with a greater force.
  • One who applies more friction force (shear force) on ground.
  • One who applies more normal force (compressive force) on ground
When a person walks on a rough surface
  • the frictional force exerted by the surface keeps him moving.
  • normal reaction of the force applied by the man on the surface keeps him moving.
  • the force applied by the man keep him moving.
  • weight of the man keeps him moving.
Which of the following helps to increase friction?
84833.png
  • Only (i) and (ii)
  • Only (ii) and (iii)
  • Only (i) and (iii)
  • (i), (ii) and (iii)
Assertion: Aeroplanes are given streamlining to increase the speed of vehicles.
Reason: Air friction decreases due to streamlining.
  • Both Assertion and Reason are true. Reason is the correct explanation of Assertion.
  • Both Assertion and Reason are true. Reason is not the correct explanation of Assertion.
  • Assertion is true and Reason is false.
  • Both Assertion and Reason are false.
State whether the given statement is true or false:
Fluid friction is more than solid friction.
  • True
  • False
Mark the correct statement:
  • Frictional force also exist when there is no motion.
  • Frictional force only exist when there is motion between two objects.
  • Frictional force is nothing but the weight of the body
  • None
Which of the following things will not happen in the world if friction were not present?
  • Dentist drilling your teeth.
  • Carpenter smoothening a wooden block.
  • Motion of cars on road.
  • All of the above
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