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We can increase Rolling friction by making the surface, on which the wheel moves, rough and also we can use rubber wheels because rubber experiences more friction than other materials.

Correct option is D) d

General uses of friction are:–

i. Friction is used to apply breaks and move vehicles.
ii. Friction is used to walk.
iii. Friction is used to hold things.
iv. Friction is used to write on paper or blackboard.

Oiling or greasing of bicycle axis reduces friction between the tyre and axis. It makes the surface between them both slippery as we know oil is smooth liquid and when we paddle and the tyre moves it moves freely and slips on the axis and does not experience metal to metal sliding.

Correct option is C) A or B

The smooth surface offers very less friction, due to which very less heat is produced by it and it is not sufficient to lighten up the matchstick.

The surface of the matchbox should be rough because when we want to burn the matchstick we should rub it only once on that surface in order to increase it’s temperature so that it could burn in order to achieve that temperature the surface should have enough friction to raise the temperature at one rub.

B) Static friction gives movement to a body

D) ball bearings

B) By striking a match stick against a rough surface

B) spring balance, brick, thread

Correct option is C) heat

Benefits of friction are as follows:

• It is not possible to even walk on the road; in the absence of friction. Walking on ice is almost impossible because of lack of friction.
• Friction is necessary to keep a ladder against a wall. The ladder will not find grip against the wall in the absence of friction.
• It is very difficult to drive on a wet road because of less friction. A thin film of water is made over the surface of road. This thin film of water greatly reduces friction. Due to this, the driver finds it difficult to control the vehicle while driving on a wet road.

Friction is directly proportional to normal force therefore friction will be doubled if the normal force is doubled.

Ball bearings are used to reduce friction between rotating shafts of machine tools. 

1. Ball bearings are used in fAnswer:

2. Ball bearings are also used in machines.

When rubber soles are used for a long time, their surfaces become smooth. Hence, the friction between the sole and the floor decreases. Therefore, slippers become slippery.

Grooves in the soles of shoes help in increasing the friction when we walk on the roads. The grooves in the shoe sole help in maintaining a grip with the ground.

Treads are made on the surface of tyres help in increasing the friction. These treads help in maintaining a firm grip on the road which reduces the risk of slipping on the road thus avoiding accidents.

Rough surface of towel helps in increasing friction, and thus provides a better grip. The towel, thus, makes it easier to open the bottle cap.

Tie a string around a brick. Pull the brick by a spring balance. When the brick just begins to move note down the reading on the spring balance that measure the force of friction between the surface of brick and the floor.

1. A moving ball stops after sometime.

2. If we push an object it will stop after sometime.

C) direct proportional

Correct option is B) more

Correct option is A) Acceleration

C) Direct proportional

Correct option is A) Lubricants

Ball bearing reduce friction between the support loads and axles of a vehicle.

Car and bicycle.

In many machines, friction is reduced by using ball bearings.

Ball bearings: The devices which reduce friction between rotating shafts of machine tools.

The differences between Sliding and Rolling friction are:–

A. Sliding Friction –

a) It is the friction acting on the plane surfaces or straight surfaces.

b) The motion of the body is accompanied by rubbing of surfaces.

c) Large amount of work is done.

B. Rolling friction –

a) It is the friction acting on round objects like wheels which then acts on the body.

b) The motion is accompanied by changing the area of contact of the wheels.

c) Small amount of work is done.

The smoothness or polished degree of both the surfaces leads to cause of friction between two surfaces, if both the surfaces are well polished or smooth then the friction will be less but the friction can’t be zero practically. Also, the irregularities lead to friction.

A rough surface will cause more friction than a smooth surface. Because, rough offers more resistance to the other surface in contact as compared to the smooth surface.

Friction depends upon the nature of the surfaces in contact with each other and at the state of motion of the object on the surface. The irregularities on the surface lead to friction. Friction depends upon the surface of both the bodies in contact and not only one. The weight of the object, if the weight of the object is high then friction is also high.

The force that opposes the motion of an object is called friction. 

Example: when we walk, friction acts in opposite direction we apply force to walk.

The factor affecting friction are: 

1. The weight of the object. 

2. The type of contact between the two surfaces.

B) Polished marble surface

Fluids are those whose which do not have any shape and flow like liquids. 

Example: Air and Blood.

(c) cemented surface

(b) decrease

(d) Friction does not act on a ball moving through air.

D) the applied force

C) temperature

(c) sprinkle talcum powder on the wooden surface. 

D) rolling friction

(b) from left to right (→)

(d) irrespective of whether the objects are solid, liquid or gaseous.

B) Rolling friction < sliding friction < static friction