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PULLEYS
The bike uses many different types of simple machines to move and stop. The simple machine that makes it go is the pedals and gears, and the simple machine that makes it stop is the brakes.
Pedals and Gears: Pedals and gears are simple machines. The chain of a bike goes in a continuous circle around one big sprocket wheel and any one of five small sprocket wheels of different sizes. When the rider changes gears, the selector mechanism called the derailer moves the chain to the correct sprocket wheel.
Brakes: The brakes are simple machines that slow the wheels down with your help. There are three different kinds of brakes. Long arm brakes are found on most mountain bikes and hybrids. The long arm brakes use two straight brake arms connected by a horizontal cable, and these brakes provide great stopping power. Cantilever brakes, otherwise known as short arm brakes, are on some hybrids and mountain bikes. The brake arms are shorter and they are connected by a triangular cable. They give plenty of stopping power, but not as much as long arm brakes. Caliper brakes are used generally on road bikes. They’re very easy to regulate but they don’t give enough stopping power.
Ideal mechanical advantage tells you how much the machine would multiply your effort force by if there were no friction. It is abbreviated IMA. (IMA = d / h) where d is the distance that you apply your force over and h is the height the object is raised.
Mechanical advantage tells you how much the machine multiplies your effort force by with friction. It is abbreviated MA. (MA = W / F) where W is the weight of the object and F is the force that you apply.
While determining efficency you can use the equation (eff = Wo / Wi), or in terms of advantage as (eff = MA / IMA)
MOTION
A force makes things move, but a force can also stop things from moving. When you pedal a bike, you use your muscles to create a force. You are like the engine for your bike. You push the pedals in a circle to start a forward motion. When you squeeze the hand brakes, you are also exerting a force which stops the motion of your bike. Motion is another name for movement. Speeding motion up is called acceleration. Slowing down motion is called deceleration.
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