# What Are Some Ways To Reduce And Increase Friction?

How you go about reducing or increasing friction depends on what type of friction you are trying to affect.

Although the science behind friction is slightly complicated, here's the short answer:

• To increase friction, you need to create a larger surface area of contact between two objects.
• To decrease friction, you need to reduce the surface area of contact.

How to reduce and increase friction
There are two main types of friction:

• Static friction
• Fluid friction
Whenever an object moves, it requires energy. Friction is the term applied to events that cause an increase in the amount of energy lost during propulsion, due to contact with another surface.

With static friction, kinetic energy is lost when two solid objects rub or press against each other.

When you rub your hands together, this seems like more effort than simply moving you're hand through the air, right? You may even feel some heat being generated between your hands as they rub.

This is all the kinetic energy that is being lost through friction (and which could otherwise be used to push your hand forward).

Reducing static friction
To reduce static friction between two solids, you need to reduce the area of contact between the two solids.

Methods such as lubrication work, because they create a layer of oil between two solids, which means they rub against the oil rather than each other. A solid loses less energy when it rubs against a liquid or a gas, and this means less friction!

Going back to rubbing your hands - if you were to dip your hands in oil, you'd notice that rubbing your hands together becomes a lot easier. This is because your hands are actually rubbing against the oil, and not against each other anymore!

Reducing fluid friction
Fluid friction is slightly different. It deals with resistance caused when an object travels through gas or liquid.

Imagine yourself walking through sand - it's pretty hard work right? Well, an airplane travelling through the air is doing pretty much the same thing, but instead of sand, it's travelling through air.

This air causes resistance - a plane has to push through it to move forward. This resistance is an example of fluid friction.

To minimize the amount of fluid friction between an airplane and the air, designers create planes that 'cut' through the air with their pointy shape.

This means that a smaller percentage of the plane's surface area has to push against the air, and this means less friction between the air and the plane.

To increase fluid friction in an airplane, you'd reverse the design so that more of the surface area of the plane is coming in contact with the air.

Here's a link to a great video that explains the whole concept of friction in more detail:
www.bbc.co.uk/learningzone/clips/increasing-and-reducing-friction
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Adding lubricant can reduce friction and Increased surface roughness can increase the friction.
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Friction can be increased by using a rough material such as sandpaper!
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