Question

Name the types of friction

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Answer 1

Friction is defined as the force that opposes the motion of a solid object over another. There are mainly four types of friction: static friction, sliding friction, rolling friction, and fluid friction. Friction and normal force are directly proportional to the contacting surfaces and it doesn’t depend on the hardness of the contacting surface. With the increase in relative speeds, the sliding friction reduces whereas fluid friction increases with the increase in the relative speed, also fluid friction is dependent on the viscosity of the fluid.

In sliding motion, each point on the body has only translational or linear motion. But in case of rolling motion, different points have a combination of linear as well as rotational motion. Look at the following figure:

Types Of friction
Figure displaying rolling motion
If we consider only the rotational motion, then point B tends to move backwards suppose with a velocity VR. Similarly, we consider only linear motion then point B moves with a velocity VL in the forward direction. Now the resultant motion of the point B will be a superposition of both the above velocities. Depending upon the values of VR and VL the rolling friction can act in the following directions:

If VR > VL then the point B tends to move backwards so as we know, friction opposes relative motion between the surfaces in contact; hence it will act in the forward direction.

Similarly, if VR < VL then the point B tends to move forward and hence the friction acts in the backward direction.

Also, if VR = VL although the ball moves in the forward direction, the frictional force acting on the ball will be zero. This is unlike sliding friction where the friction force will definitely act if the body is moving.

Friction
Types Of friction
Types Of Friction
Following are the friction types which depend on the types of motion:

Static Friction
Sliding Friction
Rolling Friction
Fluid Friction
Static Friction
Static friction is defined as the frictional force that acts between the surfaces when they are at rest with respect to each other.

The magnitude of the static force is equal in the opposite direction when a small amount of force is applied. When the force increases, at some point maximum static friction is reached.

Static Friction Examples

Following are the examples of static friction:

Skiing against the snow
Creating heat by rubbing both the hands together
Table lamp resting on the table
Coefficient Of Static Friction

The coefficient of static friction is denoted as µs. The maximum force of static friction is given as the product of the coefficient of static friction and normal force and force of static friction is less than or equal to the product of the coefficient of static friction and normal force. It is given as:

Fs max = µs η and Fs ≤ µs η
Where,

Fs is the force of static friction
µs is the coefficient of static friction
η is the normal force
Fs max is the maximum force of static friction
Sliding Friction
What Is Sliding Friction?

Sliding friction is defined as the resistance that is created between any two objects when they are sliding against each other.

Examples Of Sliding Friction

Following are the examples of sliding friction:

Sliding of the block across the floor
Two cards sliding against each other in a deck
Coefficient Of Sliding Friction

The coefficient of sliding friction is denoted as µs. The force of sliding friction is defined as the product of the coefficient of sliding friction and the normal force. It is given as:

Fs = µs. Fn
Rolling Friction
What Is Rolling Friction?

Rolling friction is defined as the force which resists the motion of a ball or wheel and is the weakest types of friction.

Examples Of Rolling Friction

Following are the examples of rolling friction:

Rolling of the log on the ground
Wheels of the moving vehicles

Answer 2

Answer:

static, sliding, rolling and fluid friction

Explanation:

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