How to Increase Friction

Q. What do you mean by coefficient of friction?explain

Q.

Why do football players have spikes on the soles of their shoes?

Q.

Friction between 2 objects is due to

1. irregularities on the surface

2. attraction between objects

3. volume of the two objects

4. repulsion between objects

Q.

On rubbing hands, we feel warm. Explain, why?

Q. Frictional force will increase if we make the contact surfaces more irregular.

1. True
2. False

Q.

How do the grooves of a tire increase the friction please explain using a diagram and a proper explanation

Q.

Liquid and gases also exert friction on object moving through them.

1. True
2. False

Q. A ball is moving on a smooth horizontal surface with a constant velocity. The velocity of the ball will be decreased if the roughness of the surface is increased.

1. True
2. False

Q. In which of the following cases, the object reaches the ground first?

1. Case 1
2. Case 2
3. Case 3
4. Case 2 and Case 3

Q. Why do kabaddi players apply coarse powder or dry soil on their hands before starting a game?

Q. In which of the following situations does fluid friction exist?

1. A box placed on the rotating floor in a vacuum chamber.
2. A missile fired to destroy enemy tanks.
3. A satellite revolving around the planet Mars.
4. A maglev train moving at a high speed.

Q. Assertion :In order to reduce sliding friction, lubricants are used. Reason: Lubrication changes the conditions of rubbing, replacing the sliding friction by rolling friction, there by reducing the force of friction.

1. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion
2. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion
3. Assertion is correct but Reason is incorrect
4. Assertion is incorrect but Reason is correct

Q. Which of the following methods can decrease the friction?

1. Making shoes with spikes
2. Applying powder on carrom board
3. Applying lubricants to machinery
4. Adding wheels in a car

Q. A Heavy uniform chain lies on a horizontal table top. If the coefficient of friction between the chain and the table surface is 0.25 then the fraction of the length of chain that can hang over one edge of the table is??

Q. Grooves, ridges, and other irregularities increase the friction on a surface.

1. True
2. False

Q.

Give reason -

Vehicles give less mileage when being driven on a rough road.

Q. Doe friction rely on area of the body it acts upon?

Q. If you want to go from one point to another point on a straight slippery path, then which of the following will be less risky?
(i) Walking with shoes with better grip
(ii) Riding bicycle
(Note that your shoes and the tyres of your bicycle are made of same material)

1. Only (ii)
2. Only (i)
3. Both (i) and (ii) are equally useful
4. Cannot be determined

Q. If a rec†an gular block is moving on an inclined plane, then the magnitude of friction is-?

Q. A block slides over a surface and it stops after covering a distance of P metres from the starting point. The same block is now slid over the same surface, but the surface is now lubricated and it stops at a distance of Q metres from the starting point.

Choose the correct option among the following.

1. 
   P > Q as lubrication reduces the friction between the surfaces.
2. 
   P < Q as lubrication increases the friction between the surfaces.
3. 
   P = Q as lubrication does not affect the friction between the surfaces.
4. 
   P < Q as lubrication reduces the friction between the surfaces.

Q. Why do kabaddi players apply coarse powder or dry soil on their hands before starting a game?

Q. A man walks over a rough surface, the angle between the force of friction and the instantaneous velocity of the person is-what? 1.22/7 2.22/14 3.44 /7 4.0

Q. Grooves, ridges, and other irregularities increase the friction on a surface.

1. False
2. True

Q.

Can you tell about Limiting force

Q. Treads help expel water out of the way so that tyres can grip well on wet roads.

1. True
2. False

Q. A block is kept on a inclined plane of inclination of length l The velocity of the particle at the end of inclined plane will be? (the coefficient of friction is ) ( Ques. refers to 8ques of MCaps- 16 medical)

Q.

Which of the following is a lubricant?

1. Rubber

2. Sand

3. Salt

4. Grease

Q. A cleaner moves his hands up and down once on a smooth glass window. Tell the direction of friction in the process.

1. First up then down
2. Smooth glass does not provide friction
3. Either up or down throughout
4. First down then up

Q. A block slides over a surface and it stops after covering a distance of P metres from the starting point. The same block is now slid over the same surface, but the surface is now lubricated and it stops at a distance of Q metres from the starting point.

Choose the correct option among the following.

1. 
   P = Q as lubrication does not affect the friction between the surfaces.
2. 
   P < Q as lubrication reduces the friction between the surfaces.
3. 
   P > Q as lubrication reduces the friction between the surfaces.
4. 
   P < Q as lubrication increases the friction between the surfaces.

Q. Why kabaddi players rub their hands with soil before they start playing?

1. For a better grip on their opponent.
2. To keep hands dry as soil will absorb the moisture.
3. To increase the roughness of the hands.
4. To decrease the roughness of the hands.