Science questions in short. [2 marks ]

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.

The heels of the shoes get wear and tear first than the rest of the shoe sole. This is because, the heel of the shoe is interacted with the ground more than the other part and due to friction, the treads of the shoe sole wear out.

This is because the paper surface offers more friction to the pencil rubber when we rub on the paper, some bits of rubber come on the paper.

When a matchstick is rubbed on a rough surface, the surface produces friction. And we know friction produces heat, therefore the matchstick lightens up.

Lubrication means applying some additive to the parts of a machine to reduce the friction. Its important because it reduces the friction between the parts of the machine. But excess lubrication can generate more heat. Example- Castor Oil, Grease.

It is difficult to move on a smooth floor because when we push the floor back there is no frictional force to stop our foot from going back and our foot keeps on going back by slipping on the surface and hence we do not get any reaction force from the ground to move forward, so it is difficult to walk on a smooth floor.

Lubricant is the name of the material which is used to decrease the amount of friction between two surfaces in contact. It is a liquid or type of oil actually.

The banana peel has fibers on it which makes it smooth and when we place our foot on it the smooth surface is in contact with the ground reducing the friction and the peel goes forward with even low force and takes our feet also with it, so we slip.

The brake pads of bicycles have to be replaced quite often because they gather more dirt, dust and the filthy matter on itself. So to allow proper functioning, they have to be replaced.

Friction offered by air is called air friction or air drag and is experienced by every moving object in order to oppose the motion, hence Yes bus experience air friction also.

Wheels are important because they are used for transportation. Heavy machines can be moved from one place to another with the help of wheels because wheels can be rolled and the amount of force is also comparatively less.

To prevent slipping of the rope from hands, Preeti has to make her hands somewhat nonsmooth, so she can rub her hands by introducing the sand between them.

Frictional force always opposes the relative motion between two surfaces and always acts opposite to the direction of motion.

When we apply brake sot the bicycle, a force of friction generates between the rim of the bicycle and the brakes. The friction is produced in opposite direction of motion. Thus, the bicycle is stopped.

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.

Power is sprinkled on the carrom board because the powder fills the cuts in the wood of the board and hence reduces the irregularity and hence the friction reduces, so the powder is used to reduce the friction on the carrom board.

If the seat cover of rickshaw is very smooth, then the friction between our body and the seat is very small. Therefore, when the brakes are applied, we tend to slip.

We apply powder to carom board because the wood has a frictional surface and to reduce the friction powder is sprinkled on the board as the powder fills the gaps on board, so the striker moves smoothly and at large distance with even lower force.

By rubbing our hands against each other we create friction between our hands and this friction produces heat. Therefore, out hands become warm.

Castor oil and Grease are the two common lubricants. Note: A lubricant is a substance that smoothens a surface. It decreases the friction of a surface.

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.

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.

They can put rollers below the heavy load. Since, the rolling friction is smaller than the sliding friction. Therefore, putting rollers below the heavy load will make this task easier for them because rolling reduces friction.

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.

While walking on the road, a man slips if he steps on a banana peel because the banana peel acts a lubricant between the road and the man’s shoe which reduces the friction. Thus, man slips on it.

After prolonged use, the mortar and pestle loose the roughness, due to which frictional force reduces and it does not work properly. So, we have to etch it to make it rough again.

Grooves mean cuts, grooves are made on a surface so that to increase the friction of the surface by increasing irregularity, for example on a blackboard when we increase the rub the chalk due to friction the chalk gets printed on blackboard, if we increase the cuts the chalk will get more deposited than previous time.

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.

The objects moving in fluids have streamlined shape so as to reduce the air drag or fluid friction that opposes their motion in any fluid.

Viscosity means simply the degree of thickness of liquid more the viscosity thicker is the liquid more friction will be offered by the liquid to an object moving through it. Hence more the viscosity more the friction of liquid.

It is easier to hold a kulhar (an earthen pot) because it more rough surface as it is made from mud. Mud offers more friction than glass and we are able to from a grip on the earthen plot.

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.

No, the object will not experience any frictional force because to experience the force of friction, two surfaces must be there and there is only one surface in this case.

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.

The objects are built in special streamline shape to reduce the drag while moving in the air. Example, birds and Aeroplane have streamlined shapes.

When the engine of a car is switched off, then there is no energy available for the engine to oppose the frictional forces. Thus, the engine slows down and eventually comes to rest.

The block having mass 2 units will require larger force to move it from the rest position because friction force increases as the mass of object increases and hence larger mass require a larger force to move from the rest position.

Spring Balance is a device which has a spring inside it which requires high amount of force to be stretched other than small springs. Its main use is to calculate the weight of substance or we can also measure friction with it.