Plowing Effect

Q. Question 19
Explain why the surface of mortar and pestle (silbatta) used for grinding is etched again after prolonged use?

Q.

Why is friction considered a necessary evil

Q.

Plowing effect as a cause for friction can be understood in which of the following cases?

1. When two rough surfaces are in contact

2. When one of the surfaces in contact is smooth and can undergo deformations in its shape

3. When both the surfaces are smooth

4. None of the above

Q. A heavy block of mass M is slowly placed on a conveyer belt moving with a speed u. The coefficient of friction between the block and the belt is y .Through what distance will the block slide on thebelt ?

Q. A bowling ball on a bowling lane is an example of __________ .

1. static friction
2. sliding friction
3. rolling friction
4. fluid friction

Q. In which of the following cases can plowing effect be a cause of friction between two surfaces in contact?

1. When two rough surfaces are in contact
2. When one of the surfaces in contact is smooth and can undergo deformations in its shape
3. When both the surfaces are smooth
4. None of the above

Q. A bowling ball on a bowling lane is an example of __________ .

1. static friction
2. sliding friction
3. rolling friction
4. fluid friction

Q. When a soft surface deforms and resists motion of a body sliding on it, this is known as:

1. plowing effect
2. adhesion
3. surface irregularities
4. interlocking

Q. In which of the following cases can plowing effect be a cause of friction between two surfaces in contact?

1. When both the surfaces are rough
2. When one of the surfaces is soft and can undergo deformation in its shape
3. When both the surfaces are smooth
4. When both the surfaces are hard and cannot undergo deformations in shape

Q. When a soft surface deforms and resists motion of a body sliding on it, this is known as:

1. plowing effect
2. adhesion
3. surface irregularities
4. interlocking

Q. When a soft surface deforms and opposes motion of a body sliding on it, this is known as .

1. adhesion
2. roughness
3. plowing effect
4. interlocking

Q. Statement I: When a brick is pushed on a soft carpet, there is friction only because of uneven interlocking of surfaces.
Statement II: When a brick is pushed on a soft carpet, there is friction because carpet has a soft surface and can undergo deformations.

1. Only statement I is correct.
2. Only statement II is correct.
3. Both statements I and II are correct.
4. Neither statement I nor statement II is correct.

Q. Which of the following is true about friction?
(a) Friction is a force that occurs only between solids.
(b) Friction is a force that only occurs on rough surfaces.
(c) Friction is a force that only occurs when an object moves.
(d) Friction can only slow things down.

Q. Question 23
We have two identical metal sheets. One of them is rubbed with sand paper and the other with ordinary paper. The one rubbed with sand paper shines more than the other. Give reason.

Q. Statement I: When a brick is pushed on a soft carpet, there is friction only because of uneven interlocking of surfaces.
Statement II: When a brick is pushed on a soft carpet, there is friction because carpet has a soft surface and can undergo deformations.

1. Only statement I is correct.
2. Only statement II is correct.
3. Both statements I and II are correct.
4. Neither statement I nor statement II is correct.

Q. Question 22
When the cutting edge of a knife is put against a fast rotating stone to sharpen it, sparks are seen to fly. Explain the reason.

Q. Statement I: When a brick is pushed on a soft carpet, there is friction only because of uneven interlocking of surfaces.
Statement II: When a brick is pushed on a soft carpet, there is friction because carpet has a soft surface and can undergo deformations.

1. Only statement II is correct.
2. Only statement I is correct.
3. Both statements I and II are correct.
4. Neither statement I nor statement II is correct.

Q. Friction does not depend on the nature of the surface in contact.

1. True
2. Ambiguous
3. False
4. Data Insufficient

Q. does friction always opposes motion ?why or why not kindly explain