Helpmyphysics

After the stormy weather of the Christmas period it was great to see the Sun shining brightly yesterday.

Actually, even though it is just past midwinter, the Sun was at its closet to the planet yesterday.
Astronomically we say the Earth was at perihelion

The fact that we are in winter is to do with the tilt of our planet which is tilted away from the Sun at the moment and nothing to do with distance from the Sun.

Anyway I wanted to capture the image of the Sun yesterday using a small compact mirror and piece of cardboard.

It is quite simple. Just make a hole in the cardboard with a pencil, just about the width of the pencil.

Sellotape the mirror onto the card over the hole.
Now carefully point the cardboard with the mirror towards the sun aiming the reflected image onto a wall a few metres away and there you have it! An image of the Sun`s disk.

WARNING! NEVER LOOK DIRECTLY AT THE SUN

It is possible to see sunspots on the image if you project it into a dark box a few metres away.

The diagram below shows how to set up your pin hole arrangement.
The mirror is placed over the hole and by moving the cardboard the image of the Sun can be moved onto a wall a few metres away.
Click the diagram below to see it larger.

I projected the image of the Sun onto my shed wall.
The mirror has the effect of increasing the distance from the pinhole ( actually the hole in the cardboard ) to the wall thus making the image larger.

Try this solar project out and see if you can capture the image of the Sun.

But I do have to emphasize: DO NOT LOOK AT THE SUN

I was a boy aged seven at Christmas 1968. I have vivid memories of getting up really early on Christmas morning and my Dad taking me round to Corpus Christi Church Calderbank for the Dawn Mass of Christmas. I was an altar boy and was chosen to serve this Mass of Christmas. The morning was very dark.

In those days Scotland `didn`t celebrate Christmas`. So Dad attended Mass with me before going back home to open our presents while he had to go off to work leaving me, my sister, Mam and our year old brother to our Christmas morning.

I remember the excitement of that Christmas Eve when three Apollo astronauts: Borman, Lovell and Anders were about to go into Moon orbit. This was the first time a spaceship had gone to the moon.

I will always feel the excitement as the news on television broadcast the message these astronauts delivered from the orbit of the moon.

The words from Genesis read by the astronauts still make my neck hairs stand on end.

But it was Jim Lovell who I remember more for his famous reply to the control centre at Houston after the big engine fired to bring the astronauts home to earth.

” Houston. There is a Santa Claus!”

As always my annual Christmas poster competition is what a scientist would like for a gift on Christmas morning.
There were some fantastic entries.
The winner is judged to be Christopher Mullen 2K
Christopher`s science lab bike caught the judges imagination.
Congratulations Christopher! Pick up your prize in the new year.

1. Runner Up was Patrick Goodfellow 1.5 for his binocular contact lenses. Geat for stargazing. Congratulations Patrick.
2. Consolation prizes judged to be great ideas were Morgan McConville`s flying shoes.
3. Anthony Hamilton`s amazing IEA machine which does everything and I mean everything! Congratulations.

A Happy Christmas from Mr Mallon.

Hi second year.

Just as promised click on the link below to download a cracking looking periodic table.
Periodic Table

Can you find how many elements naturally occur as liquids?

Hi physics lovers. Check these two videos below on internal resistance.

How to calculate the internal resistance of a cell.

Investigating the internal resistance of a cell.

Hi S4 physicists! Hope your study is going well.
Here is a Nasty 9 Quiz on Telecommunications.
Answers are on the last slide. Enjoy!

Here is an interesting poster showing the dose equivalent for various situations.
Dose equivalent is measured in sieverts.

Sievert Poster

A couple of months ago my higher physics class performed the famous egg experiment.

Could an egg be thrown at something without breaking?

Our physics tells us that to bring something to a stop its momentum must be reduced to zero.
Now there are 2 possibilities:

1. The egg`s momentum could be reduced to zero over a very short time resulting in the need for a LARGE force to be applied to the egg.
2. Or. The egg`s momentum could be reduced to zero over a longer time resulting in the need for a smaller force to be applied to the egg.

In our movie we throw the egg at a bed sheet and at a solid wooden board.
In both cases the size of the momentum is nearly the same.

So we have this equation:

impulse = change of momentum
Ft = mv – mu.
So if the egg `s momentum is brought to zero over a longish time then the force required to stop it would be small, thus the force to stop the egg wouldn`t damage it!

Could a bedsheet prove this?

You judge.

Click on the link here to take you to the PhET circuit builder.
Use the worksheet below to carry out the practical.

internalresistancePhET