Presentation on theme: "Chapter 4: Making Sense of The Universe: Matter, Energy & Gravity"— Presentation transcript:
1Chapter 4: Making Sense of The Universe: Matter, Energy & Gravity
2What Is Matter? Matter is the “stuff” that makes up our “things” Matter is composed of atoms and their constituentsThese “elements” combine to form the molecules of lifeMatter has MASS - Mass is an intrinsic property of matter
3What Is Energy?Energy comes in different forms: - Kinetic (motion) - Potential (stored) - Radiative (electromagnetic)Mass can be turned into EnergyEnergy can become MassE=mc2Energy can change type but not be created or destroyed.
5The Periodic ChartThese elements all have unique chemical properties, based on the number of protons, neutrons and electrons they are composed of.If you add or remove neutrons from the most common form of an element, you create Isotopes.Stripping electrons from an atom is called Ionization.
6Phases of Matter Solid Liquid Gas Plasma The state changes as you increase the temperature (add energy)
12Potential EnergyPotential Energy is the energy something has just because it has mass and is where it isThink of a boulder on a hill as an example, when it rolls down it turns potential energy into Kinetic Energy (U=mgh)Simply by having mass that can be turned into energy is potential…
14Kinetic Energy When mass is moved it is Kinetic Energy (T=1/2 mv2) Adding energy to a system, i.e. as heat, will make the atoms more energetic and they will move more, colliding with other atoms – this is Kinetic MotionTemperature ~ Energy
15Conservation of Energy In a closed system, the sum total of the energy is conserved
17Motion What is the difference between: Speed, Velocity & Acceleration? Speed is a scalar, that means that it is how fast you go, but without specific directionVelocity is a vector, it gives speed and directionAcceleration is found when an object is speeding up or slowing down
19Mass & MomentumMass is an intrinsic property of matter. The atomic mass is invariant, regardless of your gravitational field (or speed)Weight is a Force, it changes depending on your gravitational fieldMomentum is mass x velocity, it tells you that big-fast things are harder to stop than small-slow things.p = mv
21Newton’s Laws of Motion First Law: An object at rest remains at rest, and an object in motion remains in motion, unless acted upon by an external forceSecond Law: F = ma = Δp/ Δt Force depends on rate of change of momentum.Third Law: For every force, there is an equal and opposite force
22Conservation of Momentum Newton’s laws imply the concept of conservation of momentum. The total momentum in a system is conserved.Angular momentum acts on a body in orbit around another, held by the gravitational force. In the absence of net torque, the angular momentum remains constant. angular momentum = mvr
25Newton’s Universal Law of Gravitation Every mass attracts other mass through the force called gravityThe force of attraction between any two objects is directly proportional to the product of their massesThe force of attraction between two objects decreases with the square of the distance between their centersFg = GM1M2/d2(note that G is the gravitational constant)
27Newton’s InfluenceSome 70 years after Kepler published his three laws of orbital motion, Newton was able to explain “why” they held true!Science strives to observe, determine relationships and eventually discover “why” things work the way they do.Newton’s laws remained unchallenged until an upstart named Albert Einstein developed a general theory of gravity that was more precise in 1905.
32Gravity Rules! The gravitational influence of the Moon cause the tides Leaving the surface of Earth takes a lot of energy, it is like crawling out of a deep well. The escape velocity is about 40,000 km/hr.While the other fundamental forces (electromagnetic, strong and weak) are much stronger, their range is short and the motion of the stars and galaxies are bound by gravity.
33Free FallWhy are astronauts weightless in space? They are in a constant state of free fall. The Force from gravity in the space station from Earth is not much less than on the surface!