science project?

Question

my older sister has a kid who is doing a project on keeping an ice cold wat are good materials?

Answer 1

There are two ways to keep something cold.

1. Insulate the container to keep the heat outside. Standard household insulation, that can be found at Home Depot, will work for this. With the reflective coating on the outside it will help to reflect any heat away from the container. The building industry measures the value of this resistance in R factors. Another good way to do it is to get a normal Styrofoam cooler and improve it by wrapping it in aluminum foil.

Andrew has a good idea of using a thermos. A thermos is a metal container with another container that can fit inside. There needs to be an air gap. When you seal the two containers together then the thermos will work. One of the best insulators is a gap of air, or better yet a vacuum. Insulated Windows use the same principle. With a sealed air gap of 1/4” between two panes of glass the insulation is much better than if the two panes of glass were placed next to each other.

One way that insulation works well is to trap or allow air gaps inside the material. Spray on insulation is a binary chemical that forms a very light Styrofoam like material. The advantage of this is that it can be directly sprayed in the area to be insulated, and the excess can be cut off. Since it is a fast drying gluey substance it dries as soon as it makes contact with the air. In this way the material will stick to a wall. As the material is exposed to the air then it foams up filling the cavity, and trapping air bubbles inside the material. The expanding foam is not that powerful so if you use it in a pocket like between the inside drywall and the outside of a wall then it won’t push the drywall away from the studs to which it is nailed. Styrofoam is so light because of all the air trapped inside. You can illustrate this with a can full of marbles. The marbles are the plastic molecules, and the gap between them is the air gap. Pour water into the can until it is full. Then drain the can and measure the amount of water. This shows how much air can be trapped inside the Styrofoam.

The insulation you buy from Home Depot has air gaps between the fiberglass layers and inside those layers. The outer coating has a watertight seal with a reflective membrane to keep the water out and reflect the heat away. If the insulation gets wet then the air gaps inside of it can disappear and the layers can be compressed.

2. Remove the heat from the object. The old way was to put ice on it or inside a container. The newer method is to physically remove the heat and send it outside. In the old series the Honeymooners, with Jackie Gleason, their icebox had a larger chamber for ice, with a pan to drain it in. The refrigerator was below the ice chamber and the entire box was insulated. As the ice absorbed the heat it melted sending the warmer water out and into the drain pan.

A refrigerator uses Boyle's Law on gases and the second law of thermodynamics to absorb the heat from the container and to send it outside where it is radiated away. A gas like Freon is used because it has a melting point and a boiling point that are easily reached; of course with the CFC (Chlorofluorocarbons) problems Freon has been replaced by other gases. The Freon, as a liquid, is circulated through a pipe into a chamber inside the container to be cooled. Then the chamber is closed and a diaphram is moved increasing the volume of the container. When this happens then the chamber and the material inside absorb heat. The pressure change transferes the heat from the container into the chamber. The chamber is then opened and the gas is forced out into the radiator by the pump. As the gas is circulated through the radiator it loses its heat to the environment and can then be returned to the chamber.

To duplicate this for a science class the following materails are needed: a bicycle pump, a therometer, air tight tube (like that used in aquiram pumps), a metal can (a soup can will work) open at one end, gum or epoxy to make an airtight seal, a Styrofoam Cooler, two clamps, and a balloon.

Cut two holes in the metal can. Cut the tube in two and run one tube from the bicycle pump into the Styrofoam container and inside of the can. Then run the other air tight tube out from the can through the Sytrofaom container and outside. Seal the holes in the can with gum or a thick epoxy to create an airtight seal. Cut the balloon and stretch it over can.

This model of the refigrator is only good for one cycle. If the bicycle pump is substitued with an aquiriam pump then several cycles can be run. You can also use clear tubing with a colored liquid inside.

To operate the model start with the bicycle pump in the raised position and clamp off the outgoing air line, with the incoming air line open. Get a pinch of the balloon with two fingers and push the balloon in. Press down the bicycle pump and close the incoming air line, with a clamp. With both clamps closed pull the ballon out, then release the outgoing clamp. If a fluid is used then drain it into a bucket.

The bicycle pump is the refigrant pump. The clamps are the seals on the chamber. The metal can with the balloon over it is the chamber. They Styrofoam container is the refigrator box and the outgoing line leads to a radiatior, in this case the open air. Each pump cycle pushes air (or fluid) into the chamber, which is compressed, becaue the balloon is pushed in. When the balloon is pulled out; this decreases the pressure in the chamber so it absorbs heat from the container. When the outgoing clamp is released then the air (or fluid) carries the heat away from the chamber and into the radiator.

I have never done this experiement myself so I don’t know how much of a temperature difference you can make, you will have to use the therometer and experiment with it. The clamps can be pushed into the bottom of the Styrofoam container and held in place with gum. Then on the the knob has to be rotated. It may be possible to create a handle for the balloon by using a small wooden dowel;1/4” diameter and 1”-2” long and a tack. Nail the through the balloon into the wooden dowel then seal the whole with epoxy. Now it will be easier to push and pull the balloon in and out.

Answer 2

Depends on what grade you are in but here is a good one. Sleep Deprivation Human subjects are best but if you can not get no volunteers rats will do test their abilities in hand eye coordination concentration and memory You do this by giving simple test and video taping them as well as taking detailed notes. Then you began the Sleep Deprivation after three days test and video tape and take detailed notes of the subjects abilities to preform theses tasks after being deprived of sleep be sure to record in your notes the Speed of each response before hand and after For the memory part a multiple choice test that is exactly the same a the one given before hand is best and for the concentration have the subjects read a short book and record and note their eye movements Also record and note which subject do no make it though the project and the time they failed for hand,eye test use something soft like a beach ball and toss it to them recording and noting speed response and ability to cacth the ball Make you notes into an eye catching presentation write your findings on index cards and place them with the presentation and read them after you show the video. It is fun to di and will probably win.

Answer 3

Any insulator, like foam. Need to find stuff thats foamy, lots of holes that won't melt when it gets wet.

Answer 4

hmm... i suppose you can't bring a freezer to the school, however, most teachers have a teacher's lounge, where there is a fridge and freezer... chances are, you can barrow it... otherwise, bring an insolated lunch bag, or thermos

Answer 5

Use dust of wood. They are wonderful insulator of heat and cheap...