If you ask a friend to drive a small nail into a piece of wood placed on top of a pile of books on your head. Why doesn't this hurt you?
Well, I would want a pretty massive pile of books and a light nail.
Force times time = change in momentum.
The hammer delivers a big force for a very short time. That force on a very small nail may change its velocity quickly (big acceleration with big force because of small mass.) However the big force does not last long enough to change the speed of the pile of books much (big force, big mass, small acceleration.) Therefore the pile of books does not transmit much force on to your heard.
If you want a headache, use a sledgehammer, big 20 penny nail, and a copy of Time magazine.
Driving a small nail into a piece of wood on top of a pile of books on your head is an example of utilizing the principle of distribution of force. When the force is applied to the nail, it is distributed over a larger surface area due to the presence of the wood and the books. This distribution spreads out the force, reducing the pressure on any single point, including your head.
Here are the steps that explain why this doesn't hurt you:
1. Placing the wood: By placing a piece of wood on top of your head, you are creating a larger surface area for the force to be distributed across. This spreads out the pressure and reduces the intensity on any specific point.
2. Using a pile of books: Putting a pile of books underneath the wood further increases the surface area and supports the weight of the wood and the force applied by the nail. The books absorb and distribute the force over their surfaces, mitigating the impact on your head.
3. Distribution of force: When your friend drives the nail into the wood, the force applied gets distributed not only across the surface area of the nail head but also across the entire surface area of the wood and the books beneath. Essentially, the force is shared by the larger area of contact, which includes both the wood and the books.
4. Pressure reduction: With the force distributed over a larger surface area, the pressure exerted on any individual point, including your head, is significantly reduced. Instead of concentrating all the force on a small spot, it is spread out across the entire area in contact with the wood and books.
5. Result: As a result of the force being distributed and the pressure minimized, you do not feel any significant pain or harm when the nail is driven into the wood on top of the pile of books on your head.
It is important to note that even though the force is distributed, caution and proper safety measures should always be taken when performing potentially dangerous activities.
This scenario is an example of the principle of distribution of force and pressure. The reason why driving a nail into a piece of wood on top of a pile of books doesn't hurt you is because the weight and force of the books are distributed over a larger surface area.
When force or pressure is distributed over a larger area, it reduces the overall impact on any given point. In this case, as the nail is being driven into the wood, the force is dispersed across the entire surface of the wood, which spreads the pressure from the nail over a larger area.
Additionally, the pile of books underneath serves as a cushion, absorbing some of the force generated by the hammer when hitting the nail. This further helps to reduce the direct impact on your head.
To summarize, the combination of the wood's surface area and the cushioning effect of the books helps distribute the force and pressure, minimizing the potential pain or harm to your head.