Question

Name a machine which is used to be change the direction of force applied.

• A. single fixed pulley.
• B. single movable pulley.
• C. fixed pendulum.
• D. moving pendulum.

Answer 1

The correct option is A single fixed pulley.

A fixed pulley changes the direction of the force you exert by pulling, so you can pull down to move an object up.

In this fixed pulley system, you pull down on one side of the rope and the other side goes up. You use the same amount of force to pull down as you would to lift the toy yourself. However, you have changed the direction of the force.

A fixed pulley is useful because when you pull down, you can use your bodys own weight
to add to the push. In contrast, when you exert a force upwards by lifting something, you also have to lift the weight of your own arms. Imagine that you had a small family member sitting on a seat in the air. Would you prefer to lift them overhead with your arms, or hoist them up with a pulley system?

Remember, a fixed pulley changes the direction of the pull, but it doesn't change the amount of force you use to pull. If you have a very heavy object, you could consider building a moveable pulley. A moveable pulley supports an object with two ropes, placing the pulley in the middle. Since the pulley is being supported by two ropes, the amount of force you need to move an object is cut in half.