Last week: Temperature Definition: -Temperature is a measure for hotness and coldness and can be felt or measured with a thermometer. -Temperature measures how fast the molecules in a material are moving http://haha.nu/creative/creative-photos-by-chema-madoz

weight force on three masses Context: How much sugar do you put in your coffee? How hard do I have to push to move a car? What is the weight gallon of water, a gallon of air, or a gallon of helium? Definitions: - Mass is the amount of matter in an object, i.e. its energy content (nuclear). Inertial mass is sluggishness of an object, its resistance to acceleration. Gravitational mass is proportional to the weight of an object, the gravitational pull on the object. Discussion: (1) experimental observation: Inertial mass = Gravitational mass = Mass The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S. Lecture demos: sluggishness, weight force on three masses

weight force = mass * gravity Discussion continued … 2) Measuring mass: With a scale or balance. Units of mass: kg Units of weight force: lbs or Newton Mass of an object on the Moon = Mass of the object on earth = Mass of the object anywhere in the universe i.e. its sluggishness is the same everywhere. However the weight force is different since Gravity of earth: g = 9.8 m/s2 Gravity on the moon = (1/6) gravity on earth Therefore: Weight force is the same everywhere on earth, but Weight force on the moon = (1/6) weight force on earth weight force = mass * gravity W = m g

Beam stays horizontal if: Left mass * left distance = Discussion continued … 2) Measuring mass: With a balance. Lecture demo: Masses suspended from a balanced beam – 50gram , 20cm to the left of the center balances 20gram, 50cm to the right Beam stays horizontal if: Left mass * left distance = Right mass * right distance Lecture demo: Triple beam balance

Energy = mass * (speed of light) 2 Discussion continued … 3) Creating and destroying matter (mass) Energy (light) -> matter + antimatter -> energy (light + heat) High-energy cosmic rays impacting Earth's atmosphere (or any other matter in the solar system) produce minute quantities of matter and antimatter, such as an electron – positron pair. A positron has the same weight as an electron, but is made of anti-matter and has the opposite charge. Nuclear reactors and nuclear bombs convert matter into energy. Energy = mass * (speed of light) 2 E= m c 2 Evidence for antimatter in a bubble chamber photo (Fermilab). The magnetic field in this chamber makes negative particles curl left and positive particles curl right. Many electron-positron pairs appear as if from nowhere, but are in fact from photons, which don't leave a trail. Positrons (anti-electrons) behave just like the electrons but curl in the opposite way because they have the opposite charge. Lecture demo

Discussion continued … 4) A model for the creation and destruction of matter: The soliton machine = an array of pendulums on an elastic string Lecture demo Small regular waves represent heat, light, X-rays. Full left twist (solitons) represents matter. Full right twist (antisoliton) represents antimatter. A soliton can not be created by itself, the creation of a soliton always requires the creation of an anti-soliton, like matter can not created by itself. The creation of matter requires the creation of anti-matter. Force between solitons is attractive, like gravity. Why is there so little antimatter in our universe?

What, if the other universe is mostly antimatter? Discussion continued … 5) When solitons hit the system boundary they turn into anti-solitons. So if matter hits the boundary of the universe, does it turn into antimatter? Does the universe have a boundary? Can our universe collide with another universe? What, if the other universe is mostly antimatter?

Discussion continued … 6) Benchmark masses Mass of - 1 quart of water ~ 1kg ~ 2 pounds on Earth - a person ~ 70kg ~ 150 pounds on Earth a car ~ 1000kg ~ 2000 pounds on Earth More examples

Mass Definitions: Mass is the amount of matter in an object, i.e. its total energy content (nuclear + chemical + thermal energy). E=m c2 Inertial mass is sluggishness of an object, its resistance to acceleration. F=m a (Newton’s 2nd law) Gravitational mass is proportional to the weight of an object, the gravitational pull on the object. W = m g Inertial mass = Gravitational mass = Mass The U.S. National Prototype Kilogram, which currently serves as the primary standard for measuring mass in the U.S.