# What exactly is limiting frictional force?

• Lightning0145
In summary: Summary: When an object is sliding across a stationary surface, friction will act to slow the object down.
Lightning0145
Given that a body is moving with a constant velocity on a rough surface. Is it possible to say that if the force (which keeps the body moving with a constant velocity) is withdrawn then the rate at which it will decelerate = limiting frictional force / mass of the body? {Force = m * a}.
Thank you.

When an object is sliding across a stationary surface, friction will act to slow the object down.
Lightning0145 said:
Summary: Can I say that deceleration = limiting frictional force / mass

Given that a body is moving with a constant velocity on a rough surface. Is it possible to say that if the force (which keeps the body moving with a constant velocity) is withdrawn then the rate at which it will decelerate = limiting frictional force / mass of the body? {Force = m * a}.
Thank you.
The phrase "limiting frictional force" would be applicable to static friction. It denotes how much force it takes to "break loose" or "start skidding". Apply less force than this and a box that is at rest on the floor will not move. Apply more force than this and it will start moving.

Since you have a body that is moving, you are dealing with kinetic friction. With kinetic friction, there is just a "force of friction", not a "limiting force of friction".

In between static and kinetic friction there is stick-slip motion that you should know about.

Lightning0145 said:
Summary: Can I say that deceleration = limiting frictional force / mass

Given that a body is moving with a constant velocity on a rough surface. Is it possible to say that if the force (which keeps the body moving with a constant velocity) is withdrawn then the rate at which it will decelerate = limiting frictional force / mass of the body? {Force = m * a}.
Thank you.
I would say that you are trying to use the term "limiting force" out of context. The limiting friction force is the value of an increasing force that finally causes static friction to unstick. You seem to be discussing what happens as a force is increased until motion stops and I don't think that is what the term describes. That situation cannot be described as tightly because energy is transferred to a temperature change and the time involved would affect the situation. It's not a 'good' experiment, imo. You can get negative acceleration when any force is applied.

## 1. What is the definition of limiting frictional force?

The limiting frictional force, also known as the maximum static frictional force, is the maximum amount of force that can be applied to an object before it starts to move. It is dependent on the coefficient of friction between two surfaces and the normal force acting on the object.

## 2. How is limiting frictional force different from kinetic frictional force?

Limiting frictional force is the maximum amount of force that can be applied to an object before it starts to move, while kinetic frictional force is the resistance to motion between two surfaces when the object is already in motion. The value of limiting frictional force is typically higher than kinetic frictional force.

## 3. What factors affect the value of limiting frictional force?

The value of limiting frictional force is affected by the coefficient of friction between two surfaces, the normal force acting on the object, and the roughness or texture of the surfaces in contact. It is also influenced by the presence of any lubricants or contaminants on the surfaces.

## 4. How does limiting frictional force relate to the laws of motion?

Limiting frictional force is related to Newton's first law of motion, which states that an object at rest will remain at rest unless acted upon by an external force. When the applied force is less than the limiting frictional force, the object will not move due to the static frictional force. However, when the applied force exceeds the limiting frictional force, the object will start to move due to the kinetic frictional force.

## 5. Can the value of limiting frictional force be exceeded?

Yes, the value of limiting frictional force can be exceeded if the applied force is greater than the maximum static frictional force. This will result in the object moving with an acceleration determined by the net force acting on it and its mass.

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