How Does a Wheel and Axle Increase Mechanical Advantage?
Introduction
A machine which consists of a wheel attached to a small axle so that both of them (the wheel and axle) rotate together, and in this process force is transferred from one to another: this is defined as the wheel and axle machine. The axle is supported by a thing or a bearing which allows rotation. A small force which is applied from the wheel can amplify large loads attached to the axle. This is looked as the version of the lever. A drive force is applied tangentially to the perimeter of the wheel and a load force is applied to the axle. These two are balanced around a hinge which is known as the fulcrum.
Wheel Axle
Wheel-axel machine is a simple machine which makes tasks easier in terms of force by applying the concept of mechanical advantages. wheel and axle is assembly formed by two disks, or cylinders, of different diameters mounted together so that they can rotate together around the common axis and the thin rod that needs to be turned is called the axle and the wider object fixed to the axle, on which we are apply force is called the wheel. A tangential force applied to the periphery of the large disk can exert a larger force on a load attached to the axle thus achieving the mechanical advantage. Also the wheel and axle does not dissipate or store energy, because it has no almost no friction as well as elasticity,thus power output at the axle equals to the input by the force applied to the wheel.
Mechanical Advantage
Machines make our work easier to do. We use several machines in our daily life to make our work easier. Mechanical advantage is basically when we put a small amount of energy and a huge amount of work is done by that small energy. Being specific, it’s the ratio of force that the machine produces which is the output, to the force which is put into the machine by humans which is also known as the input. The wheel and axle comes under the category of six simple machines that are lever, pulley, inclined plane, wedge and screw. We try to use the simple machines because they give us the mechanical advantage. For example if we carry weights in our arms we will definitely feel burdened than carrying on a cart which moves on wheels. The axle and wheel are two circle-like structures that rotate together for the work to be done. The force is transferred from the axle to the wheel in most of the cases. It’s the ratio of radius of the wheel to the radius of the axle. Note- the radius is the half of the diameter and the diameter goes from the middle of the circle touching both the ends of the circle.it crosses through the origin or the midpoint of the circle. Although radii is used in the calculation of the wheel and axle but we can also do it with the help of the diameter of wheel and axle, it provides us with the same result.
Since the wheel and axle system rotates around its own bearings, thus the points on the circumference, or edge, of the wheel move faster than points on the circumference, or edge, of the axle. Therefore, a force applied to the edge of the wheel must be less than the force applied to the edge of the axle, since power is the product of force and velocity .Thus if a and b be the distances from the centre of the bearing to the edges of the wheel A and the axle B and If the FA (input force) is applied to the edge of the wheel A and the force FB at the edge of the axle B is the output, then a/b is the ratio of the velocities of points A and B is given by , so the ratio of the output force to the input force, or mechanical advantage is given by
FAQs on Wheel and Axle Explained: Physics Principles & Applications
1. What is a wheel and axle, and why is it classified as a simple machine?
A wheel and axle is a simple machine consisting of a large-diameter wheel that rotates around a smaller-diameter rod, or axle. Both components rotate together around the same central axis. It is classified as a simple machine because it helps to make work easier by changing the magnitude of an applied force, effectively multiplying the effort to move a heavier load.
2. How does a wheel and axle work to provide a mechanical advantage?
A wheel and axle works by applying an effort force to the outer edge of the wheel. Because the wheel has a much larger radius than the axle, the force travels a greater distance. This small effort force applied over a large distance is converted into a much larger output force (load) at the axle, which moves a shorter distance. This force multiplication provides the mechanical advantage.
3. What are some common examples of a wheel and axle used in daily life?
Many everyday objects use the wheel and axle principle. Some common examples include:
- A doorknob, where the knob is the wheel and the inner spindle is the axle.
- The steering wheel of a car, which turns the steering column (axle).
- A screwdriver, where the handle acts as the wheel and the shaft is the axle.
- Bicycle pedals connected to a crank (wheel) that turns the axle.
- The crank used to draw water from a well.
- A rolling pin used in the kitchen.
4. How is a wheel and axle conceptually related to a lever?
A wheel and axle can be thought of as a continuously rotating lever of the first class. The center of the axle acts as the fulcrum. The radius of the wheel represents the effort arm (where you apply force), and the radius of the axle represents the load arm (where the output force is exerted). By turning the wheel, you are essentially using a very long lever arm that wraps 360 degrees around the fulcrum.
5. How do you calculate the Ideal Mechanical Advantage (IMA) of a wheel and axle?
The Ideal Mechanical Advantage (IMA) of a wheel and axle is calculated by comparing the radius of the wheel to the radius of the axle. The formula is:
IMA = Radius of the Wheel / Radius of the Axle
A higher IMA means a greater force multiplication, indicating that a larger wheel compared to its axle will make work significantly easier.
6. In a wheel and axle system, what is the trade-off between the force applied and the distance moved?
The fundamental trade-off in a wheel and axle system is between force and distance. To gain a mechanical advantage (less effort force), you must apply that force over a much greater distance on the wheel's circumference. Conversely, the axle exerts a large output force but moves a significantly shorter distance. This follows the principle that work input equals work output (in an ideal system), so you cannot get something for nothing—you trade distance for force.
7. Does the 'wheel' in a wheel and axle system always have to be a complete, solid circle?
No, the 'wheel' does not need to be a complete circle. The key principle is applying force at a distance from the central axis (the axle). Therefore, any component that serves this purpose functions as the wheel. Examples include:
- The handle of a crank used for a well or a pencil sharpener.
- A spanner or wrench turning a nut.
- The cross-shaped handle on a water spigot.
In each case, the handle or arm acts as the radius of the wheel.
8. How does a doorknob perfectly demonstrate the wheel and axle principle?
A doorknob is a classic example of a wheel and axle. The knob itself is the wheel, and the internal rod it turns, known as the spindle, is the axle. When you grip and turn the large knob (the wheel), you apply a small amount of force over a wide area. This force is multiplied and transferred to the narrow spindle (the axle), generating enough torque to easily retract the latch mechanism inside the door, which would be very difficult to turn by gripping the tiny spindle directly.
