Week 5 Lectures Flashcards
Kepler’s Second Law
Conservation of Angular Momentum
— Tendency for an object to go around (orbit or rotate)
Ability to do work
Energy
Using a force to move something
Work
Classes of energy
Kinetic energy
Potential energy
– Bulk Motion – an object is moving
– Thermal Energy – the particles within an object are moving
– Radiative Energy – photons (particles of light) are moving
Kinetic energy
– Gravitational
– Electromagnetic
– Nuclear
– Chemical (a form of electromagnetic energy) – Rest Mass Energy E=mc2
Potential Energy
Explain Thermal Energy
As particles move faster in a contained space, heat is generated causing temperature to rise.
Energycanbetransferredfromoneformtoanother, but can never be created or destroyed.
Conservation of Energy
Question 1: ThestarGJ229hasaplanetinorbit1AUawayfrom it called GJ 229 b. GJ 229 b takes 471 days to go around its star. What does that tell you?
B. GJ 229 is less massive than the Sun.
Question #2
• When does the Earth have the most angular momentum in its orbit around the Sun?
It’s always the same
What is light
Electromagnetic Waves
Distancebetweenpeaks
Wavelength
— Particles of Light
— packets of electromagnetic waves.
Photons
Everything is both a wave and a particle
Quantum Mechanics
Shorter wavelength = __ energy photons?
Higher
Question #3
•Why do. gas clouds heat up when their gravity makes them shrink?
Gravitational potential energy transforms into thermal energy.
Question #4
• Compare how fast ultraviolet light and radio waves move through space.
Both go at the same speed.
Question #5
•Green light has a wavelength around 550nm, while violet light has a wavelength around 420 nm. What can you say about the energy of their photons?
Green light has lower energy photons
Question #1
• Which fundamental force of nature is Jalen Milroe using to make the football go forward?
Electromagnetism
Newton’s Law of Gravity
• Forces are equal and opposite.
• Force is proportional to mass.
– “Double one of the masses = double the force”
• Force follows inverse square law with distance.
– Farther apart = less force
– Force changes by more than the distance:
“Twice the distance = force goes down by more than twice as much”
How fast are you going is represented by?
Speed
Speed & direction
Velocity
Change in velocity
Acceleration
—Could be change in speed and/or direction
Question #3
• Which is not an example of “acceleration”(inthe technical physics sense)?
A car going straight at a steady 45 mph.
Newton’s Second Law of motion
When a net force F acts on a mass m it produces an
acceleration a:
acceleration = net force (F) / mass ( m)
For a given mass, more force = more acceleration
For a given force, more mass = less acceleration
totalafterbalancingopposingforces
Net Force
results from net force
Acceleration
If there is no acceleration
all forces must be balanced.
Total amount of matter.
Mass
Force you exert on something underneath you
Weight
Which is true about weightless astronauts in the International Space Station?
. They feel no weight because they are constantly falling but never landing.
Newton’s Version of Kepler’s Third Law
We can use the speed of orbits to measure mass!
