Last Week: Mass Mass is the amount of matter

1. Last Week: Mass • Mass is the amount of matter • in an object, i.e. its total energy content • (nuclear + chemical + termal energy). • E=m c2 • Inertial massis sluggishness • of an object, its resistance to acceleration. • F=m a (Newton’s 2nd law) • Gravitational massis 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.

2. Importance of a Concept The weight force on an object isconstant on Earth, whereas The mass of the object (sluggishness) isconstant throughout universe. Therefore, the on concept of “mass” is more important than “weight”. Importance of a concept =range of applicability

3. Discussion of “mass” continued … • high-energy cosmic rays produce minute quantities of matter and antimatter, such as an electron – positron pair. • - Small regular waves represent heat, light, X-rays. Full left twist (solitons) represents matter. Full right twist (antisoliton) represents antimatter. Experimental observation 0f the ceation of matter in a bubble chamber Solition machine illustrates the creation of matter. Here an antisoliton passes through a soliton.

4. Volume • Context: I drink a cup of tea. Please buy a gallon of milk. The volume of a cube with dimension r is r3. • Definitions: • The volume of a solid object measures how much space it occupies. • The volume of irregularly shaped objects can be determined by their displacement of a liquid. Lecture demo: Displacement of water by a butterfly and a sponge.

5. Density • Context: The fog is very dense. The density of wood is less than the density of water. • Definition: • The densityof a material is the mass per volume density = mass / volume Lecture demos: Archimedes In a famous problem, Archimedes was given the task of determining whether King Hiero'sgoldsmith was embezzling gold during the manufacture of a wreath dedicated to the gods and replacing it with another, cheaper alloy.[1] Archimedes knew that the irregular shaped wreath could be smashed into a cube or sphere, where the volume could be calculated more easily when compared with the weight; the king did not approve of this. Baffled, Archimedes went to take a bath and observed from the rise of the water upon entering that he could calculate the volume of the crown through the displacement of the water. Allegedly, upon this discovery, Archimedes went running though the streets in the nude shouting, "Eureka! Eureka!" (Greek "I have found it"). As a result, the term "eureka" entered common parlance and is used today to indicate a moment of enlightenment.

6. Discussion of density: • - Density of an object does not depend the shape and size of the object, just on the material it is made of • - Density of water = 1000kg/m3 = 1kg/liter • Density of a solids and fluids depend very little of the pressure and the temperature, since they are easily compressible. • However the density of gases depends on the pressure (and temperature) • Density of a gas = (molecular weight) * (pressure) / (gas constant)*temperature

7. Buoyancy Buoyancy force = Weight force of the displaced fluid Floating on an interface: density of an object is less than the density of the lower liquid, (but larger than the density of the upper liquid) Lecture demos: Floating and Sinking pop cans, Aluminum foil boat in water, Density of Water vs. Oil, Hot Air Balloon, Lava Lamp, Cartesian Diver, Density and Three Balloons, Density Paradox Set, Dry Ice & Bubbles (Density of Gases)

8. Volume • Definitions: • The volume of a solid object measures how much space it occupies. • The volume of irregularly shaped objects can be determined by their displacement of a liquid. Lecture demo: Displacement of water by a butterfly and a sponge.

9. Density • . • Definition: • The densityof a material is the mass per volume density = mass / volume Lecture demos: Archimedes