how does limiting friction vary with (a) surface area of contact (b) normal reaction
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Answer:
(a)The limiting friction depends on the nature of the surface in contact and their state of polish. It acts tangential to the two surfaces in contact and is opposite to the direction of motion of the body. Then the magnitude of limiting friction is independent of the area of contact.
(b)It is found that as the total weight pulled increases, the force of limiting friction also increases. The increase is in direct proportion. The graph shows that limiting friction F is directly proportional to the normal reaction R. it is an agreement with the law of limiting friction.
Limiting friction is the maximum amount of force that can be applied to an object to keep it from moving against a surface. It depends on several factors, including the surface area of contact and the normal reaction force.
(a) Surface area of contact: The greater the surface area of contact between two surfaces, the greater the frictional force between them. This is because there are more points of contact between the two surfaces, which increases the amount of friction that is generated. For example, if you try to push a heavy box across a rough floor with a small pointy object, it will be harder to move than if you used a larger flat object like a board.
(b) Normal reaction: The normal reaction is the force exerted by a surface perpendicular to an object in contact with it. The greater the normal reaction force, the greater the limiting friction force. This is because the normal force determines the amount of force that is pressing the two surfaces together, which affects the frictional force. For example, if you push down on a book with your hand, the normal force increases, which increases the frictional force between the book and the table.
In summary, limiting friction depends on both the surface area of contact and the normal reaction force. Increasing either of these factors will increase the limiting friction force between two surfaces.
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