Because... When you hit the head of the nail, the force you exert is concentrated right at the point - forcing it into the wood.
If you are pulling a nail out of wood, you are using a lever as a simple machine. By applying force to one end of the lever (the nail), you are able to lift the nail out of the wood using the principle of torque.
The nail presses the wood outward away from it. This compressed wood around the nail pushes back holding it in place.
a nail is sharp because the sharper the nail is, the thinner the tip is, which in turn can more easily get in between the molecules of the wood, so you can then push/smash your way into the wood, and as the width of the nail gets wider, it pushes apart the molecules, in turn, clearing the path for the nail to get through. PS. this is just common sense.
into a piece of wood
When a nail is hammered into wood, the force creates friction between the nail and the wood, generating heat due to the resistance. This heat is also caused by the energy from the impact and the compression of the wood fibers around the nail.
The point is a "wedge" that separates the wood fibers as the nail enters, making it easier to drive into the wood without tearing the wood as a flat tipped nail would.
Notably , the claw-hammer which has a flat head on one end to drive the nail into the wood and has a claw opposite of the strike head to remove the nail from the wood using the principles of leverage to extract the embedded nail from wood .
The best technique for securely fastening wood using a wood nail is to pre-drill a hole slightly smaller than the nail diameter, then hammer the nail into the hole at a slight angle to ensure a tight grip.
Turn the nail upside down on a hard surface and hit it with your hammer. A dull nail breaks through the wood and a sharp one can split the wood.
Friction is the force that holds a nail or screw in wood. When a nail or screw is driven into wood, the friction between the fastener and the wood fibers creates resistance, preventing it from easily being pulled out.
you pull the trigger and the nail shoots out and into the wood.
The claw hammer can not only hammer a nail into wood but can , by way of the claw , grasp the head of the nail and be used to pry/leverage the nail from wood .