Friction - Jharkhand Board (JAC) STD 8 Science Questions

Q 1M.C.Q. [I MARKS]1 Mark

The weight of an object can be measured by a:

A
Beam balance.
B
Analytical balance.
✓
Spring balance.
D
Physical balance.

Answer: C.

View full solution →

Q 2M.C.Q. [I MARKS]1 Mark

Ball bearing is a device which usually converts:

A
Rolling friction into sliding friction.
B
Static friction into sliding friction.
✓
Sliding friction into rolling friction.
D
Rolling friction into static friction.

Answer: C.

View full solution →

Q 3M.C.Q. [I MARKS]1 Mark

Which of the following will produce the maximum friction?

✓
Rubbing of sand paper on glazed paper.
B
Rubbing of sand paper on glass table top.
C
Rubbing of sand paper on aluminium frame.
D
Rubbing of sand paper on sand paper.

Answer: A.

View full solution →

Q 4M.C.Q. [I MARKS]1 Mark

A boy runs his toy car on dry marble floor, wet marble floor, newspaper and towel spread on the floor. The force of friction acting on the car on different surfaces in increasing order will be:

✓
Wet marble floor, Dry marble floor, Newspaper, Towel.
B
Newspaper, Towel, Dry marble floor, Wet marble floor.
C
Towel, Newspaper, Dry marble floor, Wet marble floor.
D
Wet marble floor, Dry marble floor, Towel, Newspaper.

Answer: A.

View full solution →

Q 5M.C.Q. [I MARKS]1 Mark

If the static friction between two surfaces $X$ and $Y$ is found to be $20N$, then the rolling friction between these two surfaces should most likely be:

A
$25N.$
B
$20N.$
✓
$5N.$
D
$50N.$

Answer: C.

View full solution →

Q 6Fill in the blanks: [1 M]1 Mark

Fill in the following blanks with suitable words: Friction prevents our foot from $............$ over the ground.

View full solution →

Q 7Fill in the blanks: [1 M]1 Mark

Fill in the following blanks with suitable words:
Friction always opposes $............$ between the surfaces in contact with each other.

View full solution →

Q 8Fill in the blanks: [1 M]1 Mark

Fill in the following blanks with suitable words:
Sliding friction is $............$ than the static friction.

View full solution →

Q 9Fill in the blanks: [1 M]1 Mark

Fill in the following blanks with suitable words: Objects which can move quickly through the water have a $............$ shape.

View full solution →

Q 10Fill in the blanks: [1 M]1 Mark

Fill in the following blanks with suitable words: Friction produces $............$

View full solution →

Q 11questions in short. [2 marks ]2 Marks

Which parts wear away first in shoes? Give a reason for your answer.

View full solution →

Q 12questions in short. [2 marks ]2 Marks

A pencil eraser loses tiny pieces of rubber each time you use it. Why does this happen?

View full solution →

Q 13questions in short. [2 marks ]2 Marks

Why does a matchstick light when we strike it on a rough surface?

View full solution →

Q 14questions in short. [2 marks ]2 Marks

What is meant by lubrication ? Why is it important?

View full solution →

Q 15questions in short. [2 marks ]2 Marks

Why do brake pads of bicycles have to be replaced quite often?

View full solution →

Q 16questions in short. [3 marks ]3 Marks

How can a very heavy machine be moved conveniently from one place to another in a factory? (No crane is available for this purpose).

View full solution →

Q 17questions in short. [3 marks ]3 Marks

Why are lubricants (oil or grease) applied to rubbing surfaces of machines?

View full solution →

Q 18questions in short. [3 marks ]3 Marks

Iqbal has to push a lighter box and Seema has to push a similar heavier box on the same floor. Who will have to apply a larger force and why?

View full solution →

Q 19questions in short. [3 marks ]3 Marks

Explain why, a speedboat has a streamlined shape.

View full solution →

Q 20questions in short. [3 marks ]3 Marks

Explain how, friction enables us to walk without slipping.

View full solution →

Q 21questions in details [4 marks ]4 Marks

What is drag? Give two examples of a drag force.

View full solution →

Q 22questions in details [4 marks ]4 Marks

Explain with the help of diagrams, how the use of oil reduces friction between two surfaces in contact with each other.

View full solution →

Q 23questions in details [4 marks ]4 Marks

Give an example to show that friction depends on the force with which the two surfaces are pressed together.

View full solution →

Q 24questions in details [4 marks ]4 Marks

Why are cars, aeroplanes and rockets streamlined?

View full solution →

Q 25questions in details [4 marks ]4 Marks

Explain why:
$i.$ A pencil will write on paper but not on glass.
$ii.$ Climbing a greasy pole is very difficult.

View full solution →

Q 26questions in on sentence. [1 M]1 Mark

What is the name of 'special shape' which is given to objects moving through air (or water) to reduce drag?

View full solution →

Q 27questions in on sentence. [1 M]1 Mark

When a pencil cell is released from a certain point on an inclined wooden board, it travels a distance of $35\ cm$ on floor A before it comes to rest. When the same pencil cell is released from the same point on the same inclined board, it travels a distance of $20\ cm$ on floor $B$ before coming to rest. Which floor, $A$ or $B,$ offers greater friction? Give reason for your answer.

View full solution →

Q 28questions in on sentence. [1 M]1 Mark

Why do tyres of cars wear out gradually?

View full solution →

Q 29questions in on sentence. [1 M]1 Mark

Why is it difficult to walk on a wet marble floor?

View full solution →

Q 30questions in on sentence. [1 M]1 Mark

Which force is responsible for the wearing out of car tyres?

View full solution →