pulley
Definition
A pulley is a simple machine that consists of a wheel with a groove along its rim, along which a rope or cable can be threaded. Pulleys are used to change the direction or magnitude of a force.
The most basic type of pulley is the single fixed pulley. A single fixed pulley does not change the amount of force required to lift an object, but it does change the direction of the force. This can be useful if you need to lift an object over an obstacle, such as a fence or a wall.
A single movable pulley can be used to lift an object with less force than a single fixed pulley. This is because the force is divided between the two ropes that are attached to the pulley. The more ropes that are attached to a movable pulley, the less force is required to lift an object.
Pulleys can be used in combination with each other to create even greater force magnification. For example, a block and tackle is a system of two or more pulleys that can be used to lift very heavy objects.
Pulleys are an essential part of many machines, such as cranes, hoists, and elevators. They are also used in a variety of everyday objects, such as clotheslines, window blinds, and fishing reels.
How can the word be used?
The pulley system is used to change the direction of a force.
Different forms of the word
Noun: a wheel with a grooved rim, over which a rope or belt is passed to transmit power or to change the direction of a force.
Etymology
The word "pulley" comes from the Old French word "pulleie", which is derived from the Latin word "pulleus", meaning "small ball".
The first recorded use of the word "pulley" in English was in the 14th century.
Question
What machines use a pulley?
AQA Science Exam Question and Answer
Question:
Explain the role of pulleys in mechanical systems, and provide an example of how pulleys can be used to achieve mechanical advantage.
Answer:
Pulleys play a crucial role in various mechanical systems by facilitating the transfer of force and motion. They consist of a grooved wheel and a rope or belt that runs along the groove. Pulleys are commonly used to change the direction of force, transmit rotational motion, and create mechanical advantage.
Mechanical advantage refers to the amplification of force achieved through the use of pulleys. This occurs because as the number of pulleys increases, the force required to lift a load decreases. A prime example of mechanical advantage through pulleys is found in block and tackle systems. In this arrangement, multiple pulleys are combined into blocks, with one end of the rope attached to a fixed point and the other end connected to the load. When the rope is pulled, the load is lifted, and the force required is distributed across the multiple pulleys. This arrangement not only reduces the force needed to lift the load but also enables a person to lift heavier objects that would otherwise be beyond their individual capacity.
In conclusion, pulleys serve as essential components in mechanical systems, enabling directional changes and mechanical advantage, as demonstrated in block and tackle systems.