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

A.)Single fixed pulley
B.)Single moveable pulley
C.)Fixed pendulum
D.)Moving pendulum

Hint: First we will see how the devices mentioned above work and then find the device which is used to change the direction of force applied on it.

Complete step-by-step answer:
A fixed pulley is a device that is used to change the direction of the force you pull to move an object up. You draw down on one side of the rope and go up on the other side of this fixed squash system. You are using the same amount of energy to lift your own toy. However the direction of force has been changed. A fixed pulley is useful because when you pull down, you can use your body's own weight to add to the push.

Single moveable pulley- A movable pulley is a pulley that is free to go up and down and connected to a roof or other structure by two strings of the same cord. Types of movable pulleys cover building cranes, industrial elevators and certain forms of weight lifting equipment in the gym.

While pendulum is a device which is used to measure time and find acceleration of gravity, time period and its motion is too and fro.

Hence, the correct option is A.

Additional Information- 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.

Note- 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.