The force that is applied to a machine is called the input force.

Here's a breakdown:

* Input Force: The force you exert on a machine to make it work.

* Output Force: The force the machine exerts on an object.

For example:

* Input Force: You push down on a lever to lift a heavy rock.

* Output Force: The lever exerts an upward force on the rock.

Machines can be used to:

* Increase force: A lever can amplify the force you apply, allowing you to move heavy objects.

* Change the direction of force: A pulley system changes the direction of force, making it easier to lift something.

* Increase speed: A bicycle uses gears to increase the speed at which you can travel.

Let me know if you'd like more examples or explanation on how different machines use input force!