Bed Of Nails - Revision history

imported>Stwikiadmin: /* Why This Works */

2016-03-30T14:03:33Z

Why This Works

← Older revision		Revision as of 14:03, 30 March 2016
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	==Why This Works==		==Why This Works==

	~~===Short Explanation===~~

	When we had the single volunteer stand on a single paper cup, it was crushed. This is because all of their weight is on the single cup, which is not able to support them. However, the volunteer is able to stand on several cups, because their weight is spread out over all of them. This is the idea behind '''''Pressure''''': Pressure is when you take a force, such as someone's weight, and divide it over an area. If the amount of force is constant, then you can decrease the pressure by increasing the area. This is why several of the cups can support a person, with each one taking a fraction of the weight!		When we had the single volunteer stand on a single paper cup, it was crushed. This is because all of their weight is on the single cup, which is not able to support them. However, the volunteer is able to stand on several cups, because their weight is spread out over all of them. This is the idea behind '''''Pressure''''': Pressure is when you take a force, such as someone's weight, and divide it over an area. If the amount of force is constant, then you can decrease the pressure by increasing the area. This is why several of the cups can support a person, with each one taking a fraction of the weight!

	This works just as well with the Bed and Blanket of Nails. Each nail in the bed will take a small fraction of the person's weight, so each nail has a low amount of pressure on it. The amount of pressure on each of these nails doesn't increase much when we add the blanket of nails on top, or even with the cinder block! When we smash the cinder block, the force from smashing it is spread out over the nails, and results in a very small change in pressure for each. This keeps the presenter on the bed safe from harm. This would be very different if, instead of the several hundred nails we have ~~here~~, it was only a dozen nails, or even just one. By increasing the number of nails, and therefore the area to spread the force across, we decrease the amount of pressure on each "point", and the presenter is safe from harm.		This works just as well with the Bed and Blanket of Nails. Each nail in the bed will take a small fraction of the person's weight, so each nail has a low amount of pressure on it. The amount of pressure on each of these nails doesn't increase much when we add the blanket of nails on top, or even with the cinder block! When we smash the cinder block, the force from smashing it is spread out over the nails, and results in a very small change in pressure for each. This keeps the presenter on the bed safe from harm. This would be very different if, instead of the several hundred nails we have in our Bed of Nails, it was only a dozen nails, or even just one. By increasing the number of nails, and therefore increasing the area to spread the force across, we decrease the amount of pressure on each "point", and the presenter is safe from harm.

	== Additional Information ==		== Additional Information ==

imported>Stwikiadmin: /* Why This Works */

2016-03-02T20:24:38Z

Why This Works

← Older revision		Revision as of 20:24, 2 March 2016
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	==Why This Works==		==Why This Works==

	When we had the single volunteer stand on a paper cup, it was crushed. This is because all of their weight is on the single cup, which is not able to support them. However, the other volunteer is able to stand on these cups, because their weight is spread out over all of them. This is the idea behind '''''Pressure''''': Pressure is when you take a force, such as someone's weight, and divide it over an area, such as these paper cups. If the area is big, then the amount of force is small on each cup, so they can support it. Likewise, if the area is small, then the force is high on each cup, so they are crushed.		===Short Explanation===

	This works just as well with the Bed and Blanket of Nails. Each nail in the bed will take a small fraction of the person's weight, so each nail has a low amount of pressure on it. The amount of pressure on each of these nails doesn't increase much when we add the blanket of nails on top, or even with the cinder block! When we smash the cinder block, the force from smashing it is spread out over the nails, and results in a very small change in pressure for each~~, which~~ keeps the presenter on the bed safe from harm. This would be very different if, instead of the several hundred nails we have here, it was only a ~~couple~~ dozen or even just one. By increasing the number of nails, and therefore the area to spread the force across, we decrease the amount of pressure on each ~~nail~~.		When we had the single volunteer stand on a single paper cup, it was crushed. This is because all of their weight is on the single cup, which is not able to support them. However, the volunteer is able to stand on several cups, because their weight is spread out over all of them. This is the idea behind '''''Pressure''''': Pressure is when you take a force, such as someone's weight, and divide it over an area. If the amount of force is constant, then you can decrease the pressure by increasing the area. This is why several of the cups can support a person, with each one taking a fraction of the weight!

			This works just as well with the Bed and Blanket of Nails. Each nail in the bed will take a small fraction of the person's weight, so each nail has a low amount of pressure on it. The amount of pressure on each of these nails doesn't increase much when we add the blanket of nails on top, or even with the cinder block! When we smash the cinder block, the force from smashing it is spread out over the nails, and results in a very small change in pressure for each. This keeps the presenter on the bed safe from harm. This would be very different if, instead of the several hundred nails we have here, it was only a dozen nails, or even just one. By increasing the number of nails, and therefore the area to spread the force across, we decrease the amount of pressure on each "point", and the presenter is safe from harm.

	== Additional Information ==		== Additional Information ==

imported>Stwikiadmin: /* Demonstration */

2016-03-02T14:24:20Z

Demonstration

← Older revision		Revision as of 14:24, 2 March 2016
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	# Have your co-presenter place the wooden boards across your legs, then the bucket over your head, with the edge on the blanket of nails. Then, have them place the blast shield(s) in front of the bed of nails, between the demonstration and the audience.		# Have your co-presenter place the wooden boards across your legs, then the bucket over your head, with the edge on the blanket of nails. Then, have them place the blast shield(s) in front of the bed of nails, between the demonstration and the audience.
	# Co-Presenter: Show the audience the cinder block. place the metal bars on top of the blanket of nails, and rest to cinder block across the bars, making sure the bars are not underneath the holes in the cinder block. Then, show the audience the sledgehammer, and state that you will be smashing that cinder block with the sledge hammer. Have the audience give you a countdown, and at the end of the countdown swing the sledgehammer down onto the cinder block.		# Co-Presenter: Show the audience the cinder block. place the metal bars on top of the blanket of nails, and rest to cinder block across the bars, making sure the bars are not underneath the holes in the cinder block. Then, show the audience the sledgehammer, and state that you will be smashing that cinder block with the sledge hammer. Have the audience give you a countdown, and at the end of the countdown swing the sledgehammer down onto the cinder block.
	## You do not need to hit the block hard; letting the hammer drop from a close to vertical point will give it enough energy to break the cinder block. Make sure it hits the cinder block either between the two bars or on either side of them, otherwise it might not break, and you will have to do a second swing.		#* You do not need to hit the block hard; letting the hammer drop from a close to vertical point will give it enough energy to break the cinder block. Make sure it hits the cinder block either between the two bars or on either side of them, otherwise it might not break, and you will have to do a second swing.
	# After the cinder block is broken, clear any debris off of the blanket of nails and help the presenter get up. Have the presenter show the audience that they are uninjured by spinning slowly to show no holes or injuries. They can now remove the sweater if it was worn.		# After the cinder block is broken, clear any debris off of the blanket of nails and help the presenter get up. Have the presenter show the audience that they are uninjured by spinning slowly to show no holes or injuries. They can now remove the sweater if it was worn.


	==Why This Works==		==Why This Works==

imported>Stwikiadmin at 16:19, 30 September 2015

2015-09-30T16:19:24Z

Show changes

imported>Stwikiadmin at 02:23, 11 September 2013

2013-09-11T02:23:41Z

← Older revision		Revision as of 02:23, 11 September 2013
(No difference)

imported>Stwikiadmin at 02:23, 11 September 2013

2013-09-11T02:23:41Z

← Older revision		Revision as of 02:23, 11 September 2013
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	Performer: How was your nap?		Performer: How was your nap?
	Sleeper: Great, but I had a strange dream that I was being stepped on by an elephant. Of course, it didn't hurt very much!		Sleeper: Great, but I had a strange dream that I was being stepped on by an elephant. Of course, it didn't hurt very much!

	~~Diagrams:~~

	~~http://sciencetheatre.org/phpgraphy/index.php?display=2009-03-09and10%20Delta%20County%2Fimg_5595.jpg~~

	~~http://sciencetheatre.org/phpgraphy/index.php?display=2009-03-09and10%20Delta%20County%2F034_34.JPG~~

	== Why It Is ==		== Why It Is ==

imported>Stwikiadmin: Created page with "== Age == Elementary School,Middle School,High School == Format == Stage Show == Materials == Two blast shields Equipment in black box Bed and blanket of nails..."

2013-09-11T02:21:26Z

Created page with "== Age == Elementary School,Middle School,High School == Format == Stage Show == Materials == Two blast shields Equipment in black box Bed and blanket of nails..."

← Older revision		Revision as of 02:21, 11 September 2013
(No difference)

imported>Stwikiadmin: Created page with "== Age == Elementary School,Middle School,High School == Format == Stage Show == Materials == Two blast shields Equipment in black box Bed and blanket of nails..."

2013-09-11T02:21:26Z

Created page with "== Age == Elementary School,Middle School,High School == Format == Stage Show == Materials == Two blast shields Equipment in black box Bed and blanket of nails..."

New page

== Age ==

Elementary School,Middle School,High School

== Format ==

Stage Show

== Materials ==

Two blast shields
Equipment in black box

Bed and blanket of nails
Yellow wooden foot and back supports
Black wood leg coverings (x2)
Thick gloves for sleeper (x2)
Goggles for sleeper
Sweatshirt for sleeper
Sledgehammer
Metal cinder block holders (x2)
At least 36 paper cups + 1 extra per performance

Plastic tarp
One cinder block for each performance
One backup cinder block per 3 performances

== Safety Precautions ==

Science Theatre demonstrators must keep the safety of themselves and their audience in mind at all times. All Science Theatre demonstrators must have read through the Safety Training page. The ST Safety Box with first aid kit, fire extinguisher, etc. should always be available to demonstrators. Always wear safety gloves, glasses, and a labcoat if handling chemicals; always perform potentially dangerous demonstrations at a safe distance from the audience; and always keep a very close eye on any volunteers you call from the audience. Safety is extremely important for this demonstration. If you have an audience member stand on the paper cups, hold their hand to steady their balance and instruct them to step on and off slowly. Ensure proper body support for participant in bed. Between the box, the wooden coverings, the gloves, and the goggles; the sleeper's entire body should be covered before the cinder block is put down. Keep crowd at a safe distance and behind blast shields. Make sure to tell people not to try this at home! Never invite an audience member to lie on the bed of nails.

== Preparation ==

Make sure the presenter who will be using the sledgehammer has practiced breaking the cinder block so they know how much force to use. Use as little as possible for the safety of the sleeper! Set up the blast shields between where the bed of nails will be and the audience, although you may choose to keep the bed of nails hidden at first for effect. Lay down the tarp behind the blastshield, where you will put the bed.

== Demonstration ==

For young audiences, you may want to introduce the bed of nails with a simple demonstration of pressure. Have an audience member step on one paper cup to demonstrate applying a force to a small surface area. Next, setup an array of at least 36 paper cups and place one of the black wooden leg covers on top of them. Invite another audience member to slowly and carefully step onto the board and stand there. Make sure they step onto the middle of the board, not an edge. The larger surface area of the array of paper cups should sustain their weight.

Next prepare the bed of nails. First get out the bed itself (the bed is the one without the extra wood edge on the base, which are handles) and show it to the audience. Lay the bed of nails down on the tarp. Set up the yellow wooden headrest and footrest.

Before lying down, the sleeper should take the following safety precautions. They may seem like more than is necessary, but safety is extremely important for this demonstration. Note also that the sleeper is usually a male, for anatomical reasons.

* Wear goggles
* Wear thick gloves
* Wear sweatshirt

When the sleeper is ready to lie down, follow this procedure (and see diagrams below):

* Have the sleeper slowly lie down on the bed of nails, place head in headrest, and place feet in footrest.
* Another demonstrator should then slowly hand the sleeper the blank of nails and the sleeper should lower it onto his/her chest and hold it securely by its handles (the extra wood at the edge of the base).
* The other demonstrator should place the two black wooden pieces to cover the sleeper's legs.
* The other demonstrator should use the large black box to cover the sleeper's head and neck.
* The two metal rods should be placed in the center on top of the blanket of nails and the cinder block placed on top of it. Don't leave the cinder block on the sleeper's chest for too long - it's heavy!
* Have the audience count down for you and then break the brick with the sledgehammer. This doesn't take all that much force - make sure you have practiced beforehand! This is helpful so that the sleeper is aware of the timing of the hit.

== What to Say ==

If performing the portion of the demonstration with paper cups, you can start out by asking if they would rather be stepped on by an elephant or a woman wearing high heels. Of course, the elephant applies much more force, but the area of his foot is far larger than the area of the high heel - the elephant would hurt less. Now ask why a volunteer can crush one cup, but not many. Once they start to get the right idea, point out that pressure, the phenomenon that causes a cup to crush or your body to feel pain, depends on both force and area. For young audiences, repeat this concept several times throughout the demonstration.

The bed of nails portion of the demonstration can be performed with a little humor, for young audiences. It might go something like this:

Sleeper: ...yawn...
Performer: Are you tired?
Sleeper: Yes, we've done so many demonstrations today. I'm ready to go to bed.
Performer: Well, you're very lucky, because I've brought a bed with me... put on your pajamas (sweatshirt)... here it is, a bed of nails!
Sleeper: A bed of nails? I'm not going to sleep on that, it would hurt!
Performer: No, it won't hurt at all! Back me up, guys, can you explain why it won't hurt?

Make sure the audience can explain the relationship between pressure and surface area

Sleeper: Ok, I guess it doesn't sound that bad. Yah, it doesn't hurt at all! But I'm still cold.
Performer: Well, you're even more lucky to have a friend like me, because I've also brought a blanket of 1000 nails! I know your hands are cold, too, so I've also brought these gloves. I even have a mask (black box) to shut out the light for you.

After all the safety equipment is on, the sleeper can snore loudly

Performer: Ok, he/she's asleep. Now we can try a little experiment. Since he/she's such a good friend of mine and because we're professionally trained scientists, I can try putting a cinder block on top of him. This cinder block is heavy and applies a lot of force, but you all know that it won't create very much pressure because of the large surface area of all the nails. Look, he's still sleeping! I can try applying even more force with a sledgehammer!

Now help the sleeper get off the bed.

Performer: How was your nap?
Sleeper: Great, but I had a strange dream that I was being stepped on by an elephant. Of course, it didn't hurt very much!

Diagrams:

http://sciencetheatre.org/phpgraphy/index.php?display=2009-03-09and10%20Delta%20County%2Fimg_5595.jpg

http://sciencetheatre.org/phpgraphy/index.php?display=2009-03-09and10%20Delta%20County%2F034_34.JPG

== Why It Is ==

Several physics principles are involved here. The force from any one nail is reduced by spreading the weight over many nails. The inertia of the blocks partially protects the person below from the force of impact. The smashing of the blocks absorbs much of the energy of the blow. If there were only one nail, the entire force created by the weight of the body would be distributed over the very small area presented by the tip of the one nail. In this case, the force per unit area, that is, the ratio of the force to the area, would be very great (because the area is small) and would likely result in piercing of the skin, and injury.

== Real Life Examples ==

Magic shows, feats of strength