Force and Machines
For many years, people have waged an uphill struggle against the forces of gravity and friction. Fortunately, we now have machines of all kinds to help us along the way. In this wikibook, you will explore different types of machines, find out how they work and discover that the use of simple machines to perform great feats is nothing new.
Like any other object, a bicycle starts to move only when something pushes or pulls on it. A push or a pull on something is called a force. When you ride a bike, you apply force with your legs to keep the bike moving forward. On level ground, most of your effort goes into pushing the bike forward, but when you come to a hill, you also have to work against gravity. So, when you ride up the hill you have to push your bike up against the force of gravity.
Work is done when a force moves an object through a distance. The distance must be in the direction of the force.
Friction is a force that resits the motion of one surfacer past another surface. This force creates a resistance on moving objects and causes them to stop. Wheels or rollers help cut friction between moving, touching surfaces. But you can also use a thick liquid like oil or grease to reduce friction. They are lubricants – substances that reduce friction. Grease forms a smooth layer and makes it easy for an object to slip. Ball bearings are small balls that help cut down on friction inside machines by keeping metal surfaces from rubbing against each other. A bicycle has ball bearings where the wheels are joined to the frame.
However, thanks to friction, the tires do not slip and the bike moves.
Inclined Planes are a type of simple machine. An example of a inclined plane is a ramp. A inclined plane multiplies your input force by allowing you to exert it over a longer distance. It looks like a flat, slanted surface.
The Bike of your dreams