How does a wheel and axle make work easier?
In: Engineering
A big part of it is that wheels can support a heavy weight while requiring no energy. A human holding a heavy weight off the ground has to work hard just to hold it up. In this situation the muscles are infinitely inefficient, requiring substantial chemical energy in to produce zero work out (plus plenty of waste heat).
Wheels reduce friction but an axle and wheel works like a lever and fulcrum: either you can apply a great amount of force over a short distance and receive a great amount of distance or you can apply a small amount of force over a great distance and receive a great amount of force. Think of a lever as a wheel and a fulcrum as an axle. Basically, it uses the mechanical advantage of distance to reduce the amount of force needed to move things.
Edit: maybe think of it like an axle, a fulcrum, a pulley, and a wedge all allow you to divide or spread out force over a distance and that allows you to apply more force over time (and the reverse is true as well: you can increase force applied at a smaller distance/time and have it be dispersed over a greater distance/amount of time, depending on where your fulcrum is and where you apply force).
By reducing friction? If this is what you are asking. Push a bike, now take the wheels off it and push it
There are two different answers to this depending on whether the turning of the wheel moves the vehicle or just allows the vehicle to move.
A chariot is pulled by a horse. The wheel rolls so the horse doesn’t have to drag the chariot. The rolling of the wheel reduces friction with the ground. The axle is a thinning of the wheel where it connects to the chariot and reduces the friction at that connection.
If the wheel moves the vehicle like a car, then the difference in size between the axle and the wheel acts like a lever to magnify the distance the car moves per revolution.
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