When is reducing the amount of friction useful

It is the job of the lubricant to keep these asperities apart and prevent them from contacting each other, thus lowering or eliminating metal-to-metal contact and friction. Without an adequate oil film to separate the metal surfaces, metal-to-metal contact occurs, asperities from the two surfaces weld together and then are ripped apart from each other by the motion of the surfaces sliding against each other, causing adhesion smearing and abrasion cutting. In severe cases, the two pieces of metal may weld and seize to each other.

If the oil film is sufficient to keep the surfaces separated but is too high a viscosity for the speed of the moving surfaces, then some drag or internal resistance within the fluid fluid friction will occur. This can be thought of as friction caused by layers of oil being forced to slide past each other. We encourage you to read our updated Privacy Policy Hide. Toggle navigation Toggle search.

Magazine Subscribe Today! Current Issue Archive Advertise. Factors That Affect Friction A number of factors affect the frictional conditions at the interface between these two surfaces in relative motion. These factors are: Surface Finish — The number, roughness and even the directional contact points of the asperities on the surfaces can dramatically affect the frictional coefficient. Surface Interaction It is important to understand how two metal surfaces within a machine interact with each other.

Related Articles. Ten Tips for Proper Bearing Maintenance. Featured Videos. They could explore the reasons for the wide variation in the design of shoes and in particular the soles of shoes created for specific purposes for example: running, rock climbing, ice climbing, dancing, skating and bushwalking.

Encourage students to examine the frictional advantages of each of the designs. POE Predict-Observe-Explain : ask students to predict what will happen in the following situations and then get them to observe each event before attempting to explain their observations:. After exploratory discussion, invite students to write about what a world would look like without friction. How would it be different to our existing world? What tasks could still be done and what tasks would need to be done differently?

Teaching procedure -Two Minute Bursts. This procedure has been used near the end of a unit to encourage students to make links to everyday experiences and otherwise think about what they have learnt in other ways. The teacher puts one at a time a series of provocative or 'off beat' assertions relevant to the content on the board.

The students have two minutes deliberately chosen as a short time to promote intense thinking to jot down as dot points relevant thoughts and reactions. The teacher calls for points that do and do not agree with or support the statement and then puts up the next assertion.

Our website uses a free tool to translate into other languages. This tool is a guide and may not be accurate. Fluid friction is used a lot in water parks so we can slide smoothly and fast down giant slides. Racing cyclists crouch down low on their bikes to reduce the air resistance on them.

This helps them to cycle faster. They also wear streamlined helmets. These have special, smooth shapes that allow the air to flow over the cyclist more easily. Ice causes very little friction , which is why it is easy to slip over on an icy day. However this is a good thing for ice skating and sledging. When you rub your hands together quickly the friction warms them up. Slippery substances such as oil reduce the friction between two surfaces. This is known as lubrication.

Have you ever felt as though you were walking in place when you were trying to walk into a strong wind? The air resistance is working against the force applied by your legs opposing motion and reducing acceleration.

Start your child on a tailored learning programme Weekly resources sent direct to your inbox Keep your child's learning on track. Trial it for FREE today. There are three different types of friction: Dry Friction - Dry friction occurs when two solid objects touch each other. If they are not moving, it is called static friction. If they are moving, it is called kinetic or sliding friction. Fluid Friction - Fluid friction involves a fluid or air.

The air resistance on an airplane or water resistance on a boat is fluid friction. Although liquids offer resistance to objects moving through them, they also smooth surfaces and reduce friction. Rolling Friction - Rolling friction occurs when a round surface rolls over a surface, like a ball or wheel. There are 3 main factors that will influence the total amount of friction: The roughness of the surfaces The weight of the object The surface area how much is touching.

Friction only happens with solid objects , but you do get resistance to motion in both liquids and gases. This doesn't involve sliding surfaces like friction does, but is instead the kind of resistance you get if you try to push your way through a crowd. It's a colliding situation, not a sliding one.

If the gas is air, this is referred to as air resistance. If you were in a space shuttle and re-entering the atmosphere, the bottom of the shuttle would be getting very hot. The collisions that occur between the molecules of the air being compressed by the shuttle, heat up the air AND the shuttle itself. The temperature on the top of the shuttle is also warm, but nowhere near the temperatures found on the bottom. Nobody completely understands what causes friction.

Partly, friction happens when the rough edges of one object snag on the rough edges of another object, and some of the objects' energy has to be used to break off those rough edges so the objects can keep moving. And when you rub two soft things together, like your hands, sometimes they squish into each other and get in each other's way. But even completely smooth, hard things have some friction. This friction is the result of the molecules in both objects being attracted to each other.

Friction and resistance gallery: Car tyres are engineered to use friction when braking Friction around us We need friction to light a match! How will different terrain, like gravel, affect friction? Air resistance is a form of friction The heat generated by the ice skates' blades makes some of the ice right under the blade melt; the water reduces friction under the skate and helps it slide Rubber soles on running shoes create friction, stopping us from sliding when we run!