Calculations On Friction:How to determine the coefficient of solid friction on various surfaces.

Показать описание

CONTACT FORCES: Frictional Force.
Calculations on Friction.

👉Here is the link to the theory on friction

👉Definition of friction

Friction can be defined as the force that opposes the relative motion between any two surfaces in contact.

There can be solid friction or fluid friction. Fluid friction is also called viscosity. Friction is a force of opposition, and it acts whenever there is motion or a tendency for something to move.

Hence frictional force is absent if there is no motion or if there is no force intending to cause motion.

It stops your car when the brake is applied. That is when the force producing this motion is withdrawn, friction slows down the body until it eventually comes to rest. It also prevents your foot from slipping backward when you walk.

👉Types Of Friction.

There are two types of friction, they are;

 Static or limiting friction.
 Kinetic or dynamic friction.

👉Laws Of Solid Friction

1. Friction opposes the relative motion between two surfaces in contact. It acts in the direction opposite to that of the motion.

2. The force of friction increases with the force which tends to start the motion.

3. Frictional force depends on the nature of the two surfaces in contact. That is, the nature of the surface ( rough, smooth, polished, dry, wet e.t.c.) can determine the rate at which friction will take place.

4. Frictional force is independent of the area of the surfaces in contact. That is, whether the area is small or large, Friction will take place.

5. Friction varies directly with the normal force pressing the surfaces together, i.e. it is proportional to the normal reaction R. Hence results of experiments show that the frictional force, F, is proportional to the normal reaction R between the two surfaces in contact. (F = uR).

👉Definition of the Coefficient of Friction.

The coefficient of friction is defined as the ratio of the frictional force to the normal reaction force between two surfaces. A high coefficient of friction implies that a large force is required to cause movement.

👉Determination of Coefficient of Friction.

There are five methods of determining the coefficient of static friction;

i.Horizontal plane surface with horizontal pull force method.

ii. Horizontal plane surface with inclined pull force method.

iii. Horizontal plane surface with Smooth Pulley pull force method.

iv. Inclined plane surface method.

v.Inclined Plane Surface Smooth Pulley method.

👉Advantages Of Friction And Its Uses:

Friction is desirable for several reasons.

 Friction enables us to walk on the ground and stop walking when we want to stop. We walk only with the help of friction between our feet and the ground. Without friction, we will not experience the normal reaction force which moves us forward, so we may slip and fall to the ground.

 Friction enables the automatic tire to make a firm grip on the surface of the road, hence causing movement.

 Friction helps the belt in the pulley machine to dwell in the wheel.

 Friction enables a screw or a nut to remain in place after being screwed into the position.

 Friction enables the brakes to stop the car, and the locomotive to pull the train.

 Friction is used in the grindstone to sharpen knives and chisels. The grindstone has a very rough surface which wears away the metal surface to sharpen them.

👉Disadvantages Of Friction:

 Friction leads to much wear and tear on the moving parts of machines.

 Friction causes unnecessary heating of engines. This is because the energy which must be used to overcome friction is converted into heat. Consequently, the bearings of a machine get hot when they are running.

 Friction opposes motion. The frictional force causes a loss of energy in machines and
therefore reduces their efficiency.

👉Methods Of Reducing Friction:

The frictional force that opposes motion in a moving object can be reduced in the three chief ways
below;

The use of lubricants(e.g. oil, grease, air, and graphite) The purpose of lubricants is to keep the frictional force from having direct contact between any two surfaces and thus lessen the friction between them.

The use of ball bearing; where a wheel is turning on an axle (axis of
rotation). Friction is better reduced through the use of a ball or roller bearing. These are like wheels within wheels and are precisely shaped and have hardened surfaces.

The streamlining of body shapes of moving objects. Shaping a body to streamline the fluid through which it is moving, is why modern cars, ships, and airplanes are made in such streamlined shapes to reduce the friction between them and the fluid or the medium through which they move.

👉Other supporting video links.

🤝Don't forget to subscribe and turn on the notification 🔔 .