Newton¢â‚¬â„¢s Laws of Motion - SFSU Physics & jfielder/ ¢  Newton¢â‚¬â„¢s Laws of Motion

  • View
    1

  • Download
    0

Embed Size (px)

Text of Newton¢â‚¬â„¢s Laws of Motion - SFSU Physics & jfielder/...

  • 1

    Isaac Newton (1642-1727)

    • English physicist and mathematician

    • Studied motion, light, and gravity

    Newton puts all the pieces together

    Newton’s Law of Gravity

    • Key idea: Mass • Mass is _________________________

    – NOT the same as _____ (to a scientist) – You can be weightless, but never mass-

    less

    Newton’s Law of Gravity

    • Everything with mass pulls on everything else with mass

    • Gravity is always _________ • The _____ the object, the ______ the

    pull

    Newton’s Law of Gravity

    F = -G × (Mm/r2)

    • M = • m = • r = • G = gravitational constant

    = 6.67 × 10-11 m3/s2kg

    M

    m

    r

    Newton’s Law of Gravity

    F = -G × (Mm/r2)

    • Force grows or shrinks with ________ ________ – If you get 2x closer, force is __x _______ – If you get 3x farther away, force is __x

    _______ • Called Inverse-square relation

    Newton’s Laws of Motion #1: A body continues at rest or in uniform motion in a

    straight line unless ______ _____ ___ ___ _____.

    Why doesn’t the soccer ball move on its own?

    What causes a soccer ball to roll to a stop on the grass?

  • 2

    Newton’s Laws of Motion #2: The amount of change in a body’s motion is

    proportional to the force acting on it, and along the same direction as the force.

    F (_____) = m (____) × a (___________)

    If I kick the ball this way

    ________________ ______________

    If I kick the ball harder,

    ____________

    The more _______ the body, the more _____ you need to

    change its motion

    Need ________ force to move a bowling ball

    Only need _______ force to move a ping-pong ball

    Newton’s Laws of Motion

    #3: When one body exerts a force on a second body, the second body exerts an _____ and ________ force back on the first body.

    What’s happening at the moment

    when I kick the soccer ball?

    Hint: Think about what would happen if you kicked the ball really hard with no shoes on.

    Gravity Lecture Tutorial: Pages 29-31

    • Work with a partner or two • Read directions and answer all questions carefully.

    Take time to understand it now! • Come to a consensus answer you all agree on before

    moving on to the next question. • If you get stuck, ask another group for help. • If you get really stuck, raise your hand and I will

    come around.

    The Moon and Earth pull on each other with _____ strength

    and in _______ directions

    Earth

    Moon

    Fg Fg

    You and Earth pull on each other with _____ strength and

    in _________ directions

    Earth

    Fg

    Fg

  • 3

    Wait, I thought I understood this stuff! Shouldn’t Earth feel less gravity from me? I’ve got

    a lot less mass than Earth!

    The more massive the body, the more force you need to change its motion

    Earth

    Fg

    Fg

    Which one will move more: You or Earth?

    a (acceleration) = F (force) m (mass)

    Light and Matter: Reading Messages from the

    Cosmos How do we experience light?

    • The warmth of sunlight tells us that light is a form of ______

    • We can measure the ______, or flow of energy over time, of light in units of ______

    • One _____ is about the amount of power used to lift an apple over your head in 1 second

    _____ of Light

    • White light is made up of many different _____

    How do light and matter interact?

    • Emission • Absorption • Transmission

    – Transparent objects let light through – Opaque objects block or absorb light

    • Reflection or Scattering

  • 4

    Reflection and Scattering Interactions of Light withMatter

    What is light?

    • Light can act either like a ____ or like a ________

    • Particles of light are called _________

    Waves

    A wave is a pattern of motion that can carry _____ without carrying _____ along with it

    Properties of Waves

    • ___________ is the distance between two wave peaks

    • _________ is the number of times per second that a wave vibrates up and down

    ____ ______ = wavelength x frequency

    Light: Electromagnetic Waves

    • A light wave is a _______ of electric and magnetic fields

    • Light interacts with charged particles through these electric and magnetic fields

  • 5

    Wavelength and Frequency

    wavelength x frequency = ______ __ _____ = _________

    Particles of Light

    • Particles of light are called photons • Each photon has a _________ and a

    __________ • The energy of a photon depends on its

    frequency

    Wavelength, Frequency, and Energy

    λ x f = c λ = , f = c = 3.00 x 108 m/s = speed of light

    E = h x f = photon energy h = 6.626 x 10-34 joule x s = Plank’s constant

    What is the electromagnetic spectrum?

    What is the electromagnetic spectrum? Gamma Rays •____ ____ frequency

    •____ ____ energy

    •Damaging to humans!

    •Can only be studied from space

    •Gamma ray bursts, nuclear reactions

  • 6

    X-rays

    •Still pretty high ______

    •Not as bad as ______ rays, too much is still bad

    •Medical uses

    •Can still only be studied from ______

    •Gas in galaxy clusters, supernova remnants, or the Sun’s corona

    Ultraviolet (UV) Light

    •Getting closer to visible light!

    •Too much is still a bad thing (____________)

    •Visible in supernova remnants and coming from very hot stars

    Visible Light

    •Light our ____ ___ ___!

    •Wavelengths about as long as bacteria

    •About ___ - ___ __________

    •Produced in stars

    Infrared (IR) Light •__ _____ in IR light!

    •Beyond the range of human sight

    •____-_____ _______

    •Given off by planets, some gas clouds, and moons

    Radio

    •Very wide range of wavelengths / frequencies

    •Subcategories: __, __, __, _______, _______

    •The CMB (cosmic microwave background) glows in microwaves

    EM Spectrum Lecture Tutorial: Pages 45-47

    • Work with a partner or two • Read directions and answer all questions carefully.

    Take time to understand it now! • Come to a consensus answer you all agree on before

    moving on to the next question. • If you get stuck, ask another group for help. • If you get really stuck, raise your hand and I will

    come around.