# What Happens When The Applied Force Equals the Static Friction Force?

• B
• vibha_ganji
So after it starts moving, if the applied force is lessened to equal the kinetic frictional force, it would move with constant speed.In summary, when the applied force on an object exceeds the maximum static frictional force, the object begins to move with constant acceleration. Static friction is usually greater than kinetic friction, resulting in a significant acceleration. However, if the applied force is equal to the kinetic frictional force, the object will move with constant speed.

#### vibha_ganji

In my teacher’s notes, it said that when the applied force on an object equals the maximum static frictional force, the object begins to move at constant velocity. My question is if both the applied force and the frictional force cancel as they are equal in magnitude, what force accelerates the object from zero velocity to its constant velocity?

Usually kinetic friction constant is smaller than static friction constant.
Applied force which equals the maximum static frictional force - the kinetic frictional source
would accelerate the body.
After it starts moving if applied force is lessened to equal the kinetic frictional force, it would move with constant speed.

Lnewqban and tech99
vibha_ganji said:
In my teacher’s notes, it said that when the applied force on an object equals the maximum static frictional force, the object begins to move at constant velocity. My question is if both the applied force and the frictional force cancel as they are equal in magnitude, what force accelerates the object from zero velocity to its constant velocity?
This doesn't sound right. It should be:

... when the applied force on an object exceeds the maximum static frictional force, the object begins to move with constant acceleration.

Note that static friction is usually greater than kinetic friction, so that you get a significant acceleration depending on how large this difference is. If the force is constant, then there is theoretically a minimum acceleration of ##\frac{f_s - f_k]{m}##, where ##f_k## is the kinetic friction, ##f_s## the static friction and ##m## the mass of the object. We assume that the applied force is approximately ##f_s## but just a tiny bit more.

Lnewqban and weirdoguy

## 1. What is the applied force and static friction force?

The applied force is the force that is applied to an object in a specific direction. The static friction force is the force that opposes the motion of an object when it is in contact with a surface.

## 2. What happens when the applied force equals the static friction force?

When the applied force equals the static friction force, the object will remain in a state of rest or constant motion. This is known as the equilibrium state.

## 3. How do you calculate the static friction force?

The static friction force can be calculated by multiplying the coefficient of static friction (μ) by the normal force (N) acting on the object. This can be represented as Fs = μN.

## 4. What factors affect the static friction force?

The static friction force is affected by the coefficient of static friction, the normal force, and the roughness of the surface. The greater the coefficient of static friction and the normal force, the greater the static friction force will be. A rougher surface will also increase the static friction force.

## 5. How does the value of the coefficient of static friction affect the equilibrium state?

The coefficient of static friction determines the maximum amount of force that can be applied before the object starts to move. If the applied force is less than the maximum static friction force, the object will remain in the equilibrium state. However, if the applied force exceeds the maximum static friction force, the object will start to move in the direction of the applied force.