# Calculating frictional force given mass and coefficient?

In summary, the mass of a steel block is 760.9 g and the static coefficient of friction is 0.15. To find the frictional force in Newtons, the area of the block in contact with the surface needs to be known. The coefficient of friction is a scalar value and can be multiplied by the mass in kg to determine the force required to support the object. However, the kilogram is not a unit of force, so the force required to support the object should be determined using the mass and local acceleration of gravity. The maximal value of static friction can be calculated using the coefficient of friction and normal force, and sliding friction can be approximated by multiplying the coefficient of friction by the normal force.
The mass of a steel block is 760.9 g, the static coefficient of friction is 0.15, how do i find the frictional force in Newtons?

The area of the block in contact with the surface needs to come into the picture.

The mass of a steel block is 760.9 g, the static coefficient of friction is 0.15, how do i find the frictional force in Newtons?
You can't, from this information.
anorlunda said:
The area of the block in contact with the surface needs to come into the picture.
How would that help?

0.00032258 meters^2

anorlunda said:
The area of the block in contact with the surface needs to come into the picture.

A.T. said:
You can't, from this information.
How would that help?

OK, and the unite of the coefficient 0.15 are what?

anorlunda said:
OK, and the unite of the coefficient 0.15 are what?
anorlunda said:
OK, and the unite of the coefficient 0.15 are what?
I thought Coeff of friction was the ratio of Frictional force to force pushing the bodies together, it is scalar, right?

I thought Coeff of friction was the ratio of Frictional force to force pushing the bodies together, it is scalar, right?

I beg your pardon, you are correct.

anorlunda said:
I beg your pardon, you are correct.
So multiply 0.15 by mass in kg?

So multiply 0.15 by mass in kg?
The kilogram is not a unit of force. It is a unit of mass. Given an objects mass and the local acceleration of gravity, you can determine how much force is required to support it, however.

jbriggs444 said:
The kilogram is not a unit of force. It is a unit of mass. Given an objects mass and the local acceleration of gravity, you can determine how much force is required to support it, however.
Ok, I got 7.45 for the force required to support it, and 0.15 x 7.45 is 1.118 Newtons. Look good?

Yes. 0.15 times 7.45 Newtons is 1.118 Newtons.

Ok, I got 7.45 for the force required to support it, and 0.15 x 7.45 is 1.118 Newtons. Look good?
Note that this is not the actual static friction, just the maximal value it can reach given a normal force of 7.45N.

Abhirikshma and jbriggs444
Usually, F=mu*Wt frictional force equals some constant (coefficient of friction) times normal (perpendicular) force. Although there are differences between sliding friction and static friction, their correlation is close to 1. That doesn't mean they are equal.

Sliding friction can often be approximated by F=mu*N. You know mu, you know N (normal force). Sliding friction is almost constant for slow sliding (<<<<<<<<<<c).

max static friction calculated as 1.118 Newtons is correct provided there is no vertical acceleration of the surface, and it is perfectly horizontal.

## 1. What is frictional force?

Frictional force is the resistance force that opposes the motion of an object when it comes into contact with another object or surface.

## 2. How is frictional force calculated?

Frictional force can be calculated by multiplying the coefficient of friction (μ) by the normal force (N), which is the force exerted by the surface on the object. The formula is F = μN.

## 3. What is the coefficient of friction?

The coefficient of friction is a dimensionless constant that represents the amount of friction between two surfaces in contact. It is dependent on the materials and surface texture of the objects.

## 4. What is the normal force?

The normal force is the perpendicular force exerted by a surface on an object in contact with it. It is equal in magnitude and opposite in direction to the force of gravity on the object.

## 5. How does mass affect frictional force?

Generally, the greater the mass of an object, the greater the frictional force it will experience. This is because a heavier object exerts a greater normal force on the surface, resulting in a higher frictional force.

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