Physics 12

Mr. Jean

December 12th, 2012

The plan:

• Video clip of the day

• Santa’s Diet

• Bar Magnets

• Right Hand rules and videos

Santa’s Diet

• A full glass of milk and 3 cookies per household in 31 hours… So 91.8 million servings of the above diet… Ummm...

• What does this mean?

A full glass of milk:

• 2% - 120 calories

• 1% - 100 calories

• Skim - 80 calories

• Even with Skim Milk that is a minimum total of 7344000000 calories.

• MILK'S BASIC CONTENTS

• ALL cow's milk (regular and 'organic') has 59 active hormones, scores of allergens, fat and cholesterol.

• Most cow's milk has measurable quantities of herbicides, pesticides, dioxins, and up to 52 powerful antibiotics.

• Cow's milk can have traces of anything the cow ate... including such things as radioactive fallout from nuke testing ... (Strontium-90).

Also, just remember:

• The average human body can NOT physically hold down more than a gallon of milk in one serving…

• Your body will activity (and violently) reject any more milk and it is not pretty nor does it smell nice.

• A single cow yields about 90 glasses of milk per day or about 200,000 glasses of milk per lifetime.

• So to supply Santa’s Milk binge we would need 1.2million cows producing milk at peak capacity. – This is probably the most plausible fact

Now, the cookies:

Key assumptions about the cookies:

– Maximum of 3 cookies per trip

– All cookies follow a reasonable calorie range between 150 – 300 per serving.

– Cookies are warm, fresh and very delicious.

Total Calories from Cookies:

• On average 200 calories per serving.

• 91.8 million servings in 31 hours

• 1.836 x 1010 Calories (for the journey)

• Which is a staggering 756 000 000 calories per hour.

Calories a human needs to survive:

• Typical human diet: 2000 Calories a day

• Typical human life expectancy: 75 years

• A human in a life time will need roughly 5475000 calories.

• Santa eats 138 life times worth of calories per hour. (In cookies alone)

In conclusion:

• Santa’s costume must expand.

• 22.9 million litres would fill approximately 9.18 Olympic swimming pools.

• 18.4 million kilograms of cookies would be roughly ½ the mass of the titanic.

• Santa probably only eats once a year.

• You cannot "break" magnets into separate "monopoles".

• Poles always come in pairs.

Second Right Hand Rule:• SECOND right hand rule (p. 764):

– Grasp the coil with your right hand with fingers pointing in direction of current. Your thumb points towards the N pole of the magnet.

Parallel Wires:

• Oersted discovered that an electric current produces a magnetic field.

• In 1822, Michael Faraday was able to show that a changing magnetic field could produce electric current. When the switch was closed (ie. steady current), there was no deflection on the galvanometer.

• Faraday noticed a deflection only when he closed OR opened the switch.

• A CHANGING magnetic field can produce an electric current. This is the induced current.

• The relative motion between the wire and the magnetic field produces current. The process of generating current through a circuit is electromagnetic induction.

• Basic principle of electromagnetic induction:– whenever the magnetic field in the region of a

conductor is moving or changing in magnitude, electrons are induced to flow through the conductor.

• When the magnetic field through the coil changes, a current flows as if there were a power source. – aka: EMF (electromotive force) in the circuit.

• A battery or any device that transforms one type of energy (mechanical, chemical) into electrical energy is a source of EMF (power source).

• Inside the battery or device, there is internal resistance. No matter how efficient the device, there will be energy losses inside the device.

• The potential difference, V, inside the battery (caused by chemical reactions) is the EMF.

• IF THERE IS NO CURRENT FLOWING, the terminal voltage is equal to the EMF.

• When Faraday moved a magnet through the coil, he generated electrical energy (induced a current).

• This electrical energy came from the moving magnet (kinetic energy).

• This transfer of energy is WORK. Work required a force.

Prior to Christmas: • Lenz’s Law• Magnetic Flux• Direct Current

– Generators– Motors

• Alternating Current– Generators– Motors

• Transformers (Not the movie… maybe…no!..)

E = MC2

• First 20 minutes with about Michael Faraday