Here's why:

* Lever: A lever is a simple machine that uses a rigid bar to amplify force. It consists of a fulcrum (pivot point), an effort (force applied), and a load (resistance to be overcome).

* Hammer as a Lever: When you use a hammer to pull a nail, the hammerhead acts as the lever arm, the nail acts as the load, and the fulcrum is the point where the hammer handle meets the nail head. By applying force (effort) to the handle, you increase the force applied to the nail, making it easier to pull out.

Let me know if you have any other questions!