My PBL Project

Introduction:

Bed of nails is a project in which the equal distribution of mass among multiple pressure points is demonstrated. When a body of mass lies on the surface full of nails, the weight is equally distributed to the tips of the nails. In order to avoid injury during the demonstration process, it’s crucial that all of the nails are positioned at the same height. Whereas only 1 nail would penetrate the skin as a result of too much mass on one pressure point, multiple nails enable the equal division of weight among the nails so that the body could lay on the nails unharmed.

Driving Questions:

• How does a person lay on a bed full of nails without getting harmed?"

-When a body of mass lies on the surface full of nails, the weight is equally distributed to the tips of the nails. Whereas only 1 nail would penetrate the skin as a result of too much mass on one pressure point, multiple nails enable the equal division of weight among the nails so that the body could lay on the nails unharmed.

• What is the Pressure Formula?

-Pressure Formula is Pressure= Force/Area. It's used to calculate the pressure on given points based on the force that is being applied upon the point and the area of the point.

• How was the Bed of Nails used in the past?

-The bed of nails has been used by yogis in India and the eastern world for centuries during the ancient times. Yogis would use the bed of nails to meditate and relax the mind as well as the body.

• What are other uses of the Bed of Nails?

-Other uses of the bed of nails in history are related to the treatment of physical conditions. Since technology was nowhere as advanced as it is today, people with back pain couldn't get rid of the pain. Once the bed of nails were developed, it helped people with back pains by relieving their pain. The bed of nails relieves back pain by pressuring back muscles and basically massaging them.

Materials:

• • 2 pieces of wooden board (30 x 91 cm in this case)

  • A lot of of nails (around 2700)

  • Glue gun and a large supply of glue sticks

  • A drill with an appropriate drill bit

  • A meter stick

  • Permanent Marker

Procedure:

1. Obtain materials

2. Use the meter stick and the permanent marker to draw lines that are spaced 1 cm from each other along the horizontal and vertical axes on the plywood. This will result in squares with sides that are 1 cm long.

3. Using an appropriate drill bit, drill holes in every point where the lines intersect. This is the most time-consuming part of the project. Spacing of the holes must be exactly 1 cm. Make sure that all of the holes are drilled straight through. Have a supervisor help you if necessary.

4. Place the nails in the holes. The holes shouldn’t be too big so that the nails don’t fall through them.

5. When all nails are appropriately placed in the holes, check the height of the nails. All of them must be of equal height for this experiment to work properly.

6. Seal the back of the nails to the board using the glue gun. Afterwards, attach the other piece of board behind the glued part to secure the position of the nails completely.

7. Install the headrest at one end of the board.

Safety:

Be very cautious when drilling holes on the plywood and handling the nails as splinters from the plywood and the sharp tip of the nails can puncture skin. Have your teacher or an elder observe you as you drill holes if necessary. While drilling the holes, wear goggles since the dust of the drilled plywood will be flying around. If the dust gets in your eyes, flush thoroughly. Also, wear an apron to avoid getting your clothes dirty. Do the drilling process outside.

During the demonstration process, make sure the bed of nails is positioned so that no one will accidentally fall on to it and injure themselves. Caution the people who try it beforehand, the most dangerous part of the demonstration is when the body is being lowered or raised from the bed of nails. During these times, the weight of the body will be applied on a decreased amount of nail tips. To avoid injury, makes sure that a person is positioned correctly above the bed before he/she lays onto it. Assist the person if necessary.

Pictures:

Scientific Principal:

The science behind this project ties back to the pressure formula:

The pressure formula represents the idea that as the area that the force is applied on increases, pressure decreases. Similarly, in the "Bed of Nails" project, a body lays on numerous nails and doesn't get punctured. The reason behind this is because about 2700 nails are supporting the weight against the Earth's gravitational pull on the mass. As the nails connect with the body, the pressure on the tip of any individual nail is too small to pierce the skin.

Real Life Connection:

The bed of nails is being used as a treatment for back pains that may develop due to old age or any other reason. There are examples of this in the history: the bed of nails has been used for thousands of years. Recent uses of the bed of nails include magic tricks and physics demonstrations. A famous example requires a person to lie on a bed full of nails with a board on top of the chest. Cinder blocks are placed on the board and smashed with a sledgehammer. The person is unharmed.

Action Video: