A pulley is a simple machine that helps lift up objects by reducing the force needed to raise it. It consists of several parts: a cord, two or more fixed wheels with grooved rims, support beams and the weight required to carry. As shown in the diagram below, the wheels are fixed in position with the help of two support beams and the cord is wrapped around them. At one end of the cord is the pulling force, while at the other is a fixed support beam. The load hangs off a support beam attached to the bottom wheel, which the cord passes through and supports underneath. Therefore, the original weight of the object is x amount of Newtons whearas the force needed to lift it a would be only x/2 Newtons. This is due to the fact that there are two cord segments directly supporting the weight, dividing it evenly between the one connected to the support beam and the one to be pulled on. In a pulley system, the wheels are usually made up of either a metal alloy or rubber, while the cord can made up of strong nylon or cotton. Support beams are generally consisted of metal alloys. Examples of machines that use pulleys are: garage doors, cranes, wells and flagpoles.
The inclined plane is a simple machine which is used as an assistance for raising or lowering weights. Instead of applying large amounts of force on an object by lifting it up directly, the inclined plane enables users to raise the same load with less force but more distance. Using the formula Work = Force x Distance, the overall work required for the two methods are the same but the latter is more useful when lifting heavier weights. Inclined planes also have benefits when lowering loads, since the object can travel down itself by gravity without anyone needing to apply force to gently lower it (so, if fragile, it does not break).
In the above analysis of the forces acting on an inclined plane, gravity can thought of as two separate forces with different directions which, when combined, equals itself. The first branch, F1, is cancelled out by its equivalent opposite force (according to Newton's Third Law). The second branch, F2, would on its own cause the load to slide down the ramp. However, the presence of friction diminishes the magnitude of Force 2 and results in the load travelling at a pace determined by the angle of the slope of the incline plane. Inclined planes are made up of solid materials, such as metal or plastic. Several machines use inclined planes, such as wheelchair ramps and slides
*Newton's third law states that for every force between two objects or things, there is an equal and opposite force. For example, if a someone pushes a wall, he or she will receive the same amount of force back to their hand. **Diagram's forces are not to scale. Angle between F1 and gravity an angle between F2 and gravity is intended to be equivalent.
A wedge is a simple machine that is used for splitting objects apart. It functions by converting forces applied to its blunt edge into forces perpendicular to its inclined surface. The effectiveness of this type of device can be measured in mechanical advantage, or the ratio of slope length to width. A shorter and thicker wedge is harder to push in but does its job quicker, whereas a longer and thinner wedge is easier to push in but less effective. Wedges can be made up of anything hard and solid, such as wood or metal. Examples of machines that use the wedge include the knife, axe, scissors, and shovel.
Screws are simple machines that are used to fasten things in place. In order to drive a screw into something, it needs to be turned in the right direction indicated by its threads. During the process of placing a screw into something, the turning force is converted into force going downwards. Screws are generally made up of metals, such as stainless steel, brass and aluminium alloy. This is so that they can last longer and pin things in their proper places. Instances of machines that use screws include drill bits and corkscrews.
A lever is a simple machine that enables people to complete their task more effectively by multiplying force. It consists of a rigid bar that pivots about a fulcrum as well as a load and effort. The part where people apply force to is called the effort, and the object to be moved is called the load. The distance from the fulcrum to the effort is known as the input arm, while the distance from the fulcrum to the load is called the output arm. Its mechanical advantage is seen when you can move an object using less force than its weight, or when you can move an object further distance than you apply to the lever. There are three classes of levers, each of which has their own type of mechanical advantage. A first-class lever means that the fulcrum is in the middle and is closer to the effort than the load. Although it will require more force to push down, the load will rise further and thus a mechanical advantage has been achieved.
Class 1 Levers
The fulcrum in a second class lever is at the end of the bar and effort is at the other end, making the load in the middle. This type of lever requires more distance to raise, but much less force is needed when doing so.
Class 2 Levers
The fulcrum in the the third-class lever is also at the end of the bar, but the effort and load has switched places from the second-class lever. Instead of being in the centre, the load is now at the other end and the effort is in the middle. Similar to the first-class lever, this type increases distance raised but needs more force.
Class 3 Levers
Levers are made up of hard, solid substances such as stainless steel and metal alloys. Some examples of machines that use levers are wheelbarrows, crowbars, and scissors.
The wheel and axle is a simple machine that is designed for making travel or transportation easier. It is comprised of two parts: the axle, which is the rigid bar, and the wheels, which are attached to either side of the axle. The advantage of moving using a wheel and axle lies in the fact that the wheels have a larger diameter than the axle. When an effort is applied to the axle, the force is multiplied since the wheel rotates more distance. Not only will it increase force, but it will also experience less friction. Thus, moving something on a wheel and axle is much easier than dragging or pushing it along on the ground. The wheels can be made up of any material, although in most cases it is rubber and the axles are usually made up of metal alloys. Examples of machines that utilise the wheel and axle include the car, bus, bicycle and skateboard.