Science Fair at the Science Camp

Wow, it is sooooo hot and humid these days in Toronto.

And like every summer, Toronto is bustling with tourists.
But more than that, Toronto is a popular place for people from all over the world to come and improve their English skills, while soaking up sun and sites of this gorgeous place.

How does that have anything to do with science?
Well, as it happens, this last Saturday, as part of the Pueblo Science experience, we held a "Science Fair" event for the CISS ESL camp at St. Michael's University.

We had a GREAT time!!!!

We had:

Balloons pushed into Liquid Nitrogen

What you see:
When an inflated balloon is pushed into liquid nitrogen it shrinks.
When taking it out of the liquid nitrogen, it expands back to its former size.

Why does that happen?
That's because the trapped air inside shrinks when the temperatures drop, and expands when the temperature increases.
The pressure inside is always constant at 1atm, same as in the atmosphere.
The amount of air molecules which are mainly nitrogen molecules and oxygen molecules is kept fixed because the balloon is closed tight.
The only two variables left to be changed are the temperature (liquid nitrogen is at -196 centigrade!) and the volume.
The relation between all these attributes (pressure, volume, amount and temperature) is called:
The Ideal Gas Law, which is P*V = n*R*T
(P is the pressure,
V is the volume
n is the amount of molecules
T is the temperature
and R is a constant that relates all of the above to one another and is called not surprisingly - the gas constant) 

 

We also had:

The Disappearing Vial

 What you see:

When you submerge a glass vial into a glass filled with oil, the vial becomes invisible!!!!!!

Why does this happen?

The reason we can see things is because light hits them, bounces back, and hits our eyes.

But the medium around the object also plays a role.

For instance, we look at a coin on the table, it is easy to see it and grab it.

But when the coin is in a pool of water, we see it, but have a herder time grabbing it.

This is because the water bends the light as it penetrates it. This bending of light is called REFRACTION, and the extent by which light is refracted is called "Refractive Index"

When light passed from one medium (say water) to another medium (say glass) the light will bend if the refractive indexes are not the same. 

BUT, if the refractive indexes are the same (like in our case with oil and glass), then light passes through without bending (or, refracting) going straight through. This makes the glass appear invisible!

 

 

 And also:

Non-Newtonian Fluid

 What you see:
When you mix corn starch and water, you get a gooey mixture (very slimy).
When you push your finger in it slowly, it goes all the way in.
When you pound it hard and fast, it cannot penetrate. The mixture appears 'solid'.

Why does that happen?
Newton was able to formulate how fluids behave by stating that when you apply a force on them, the fluid will flow. But like all motion, fluids experience "friction" which is referred to as viscosity.
What Newton saw was that viscosity was constant of the material, and only changed with temperature.
However, some fluids (like our corn starch) behave differently. (therefore the term - "non-Newtonian")
Our stuff 'solidifies' with strong force, meaning its viscosity increases with force.
When the force is weak, the viscosity is lower.

There were a few more activities, but I think this post is long enough.
I'll continue this another time.
Stay tuned....