Final answer:
A hammer is used to drive and pull nails, with safety precautions such as wearing glasses to prevent injury from metal slivers. Nails can bend unless force is distributed evenly, and nail tips can exert tremendous pressures with sufficient force applied. A nail puller in equilibrium applies a constant rate of force, and a longer handle offers greater mechanical advantage.
Step-by-step explanation:
A hammer is used to drive and pull nails. Always wear safety glasses because you are hitting metal, the hammer, against metal, the nail, and little slivers of metal will be flying. An old carpenter's trick to prevent nails from bending when pounded into hard materials is to grip the center of the nail firmly with pliers, which helps by distributing the force applied more evenly along the nail's shaft, reducing the likelihood of bending. Nail tips exert tremendous pressures when hit by hammers because they exert a large force over a small area. To create a high pressure of 3.00 × 10⁹ N/m² with a nail that has a circular tip of 1.00 mm diameter, a significant force must be applied. This is achieved because the hammer strikes the nail and is brought to rest in a very short distance, resulting in a high pressure. When using a nail puller, a lever with a large mechanical advantage, the nail puller is in equilibrium when pulling a nail at a constant rate. However, if you pull the nail with acceleration, the nail puller is no longer in equilibrium, and the force applied to the nail puller is larger due to the additional force required to accelerate the nail. The length of the handle on the nail puller is directly related to the force you can apply, as a longer handle provides a greater mechanical advantage.