machines [3] [pulleys] [1] [comprehension quiz]

A pulley is a simple machine that consists of a rope wrapped around a grooved wheel. Pulleys are generally used to lift a load. There are three types of pulleys: fixed pulleys, moveable pulleys, and compound pulleys. Compound pulleys consist of two or more fixed and moveable pulleys. A fixed pulley has a wheel that is secured in a single spot and changes the direction of the force. The pulley itself stays in place while the load moves with the rope. A movable pulley has a pulley attached to the object; one end of the rope is attached to a fixed point and the other end of the rope is free. A compound pulley is a combination of a fixed and movable pulley to maximize the mechanical advantage of the system [we will cover this later] An example of a fixed pulley would be a simple flagpole where a flag can be raised to the top of the pole by simply pulling on a rope which goes around a pulley. An example of a fixed and movable pulley would be window blinds. In this system, the rope is attached to a fixed (non-moving) point, the pulley is attached to the object. An example of a compound pulley system is found on a construction site crane. This uses multiple ropes and pulleys to distribute the load, making it easier to lift heavy loads. Here you can see them all individually separated.

1. Pulleys are generally used ? to pull a load to push a load to lift a load 2. How many types of pulley are there ? 2 3 4 3. Which of theses statements is wrong ? compound pulleys can have only one pulley compound pulleys can have more than two pulleys compound pulleys can have more than three pulleys 4. An example of a fixed pulley is ? a flagpole a window blind a crane 5. An example of a movable pulley is ? a flagpole a window blind a crane

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