Download Linking Asteroids and Meteorites through Reflectance

Astronomy 101
The Solar System
Tuesday, Thursday
2:30-3:45 pm
Hasbrouck 20
Tom Burbine
[email protected]
Course
• Course Website:
– http://blogs.umass.edu/astron101-tburbine/
• Textbook:
– Pathways to Astronomy (2nd Edition) by Stephen Schneider
and Thomas Arny.
• You also will need a calculator.
Office Hours
• Mine
• Tuesday, Thursday - 1:15-2:15pm
• Lederle Graduate Research Tower C 632
• Neil
• Tuesday, Thursday - 11 am-noon
• Lederle Graduate Research Tower B 619-O
Homework
• We will use Spark
• https://spark.oit.umass.edu/webct/logonDisplay.d
owebct
• Homework will be due approximately twice a
week
• I will drop the lowest homework score.
HW #2, #3, #4
• I will go over the answers
• http://blogs.umass.edu/astron101-tburbine
Exam #1
•
•
•
•
•
Review questions are online
Thursday
40 questions
Multiple choice and True/False
Review session:
– Wednesday 6-7 pm in Hasbrouck 20
http://www.hulu.com/watch/63319/cosmos-the-harmony-of-the-worlds
Acceleration
• Acceleration is when your velocity is changing
• Velocity not changing, no acceleration
Acceleration
•
•
•
•
•
a = ∆v/∆t
Car is travelling at 10 m/s
Increases its speed to 30 m/s over 5 seconds
a = (30 m/s – 10 m/s)/5 seconds
a = 4 m/s2
Difference between mass and weight
• Mass is the amount of matter in your body
• Weight is the amount of force acting on your
body
• So on the Moon, you would have the same mass
as on Earth but weigh less on the Moon since the
Moon is less massive than Earth
Isaac Newton (1642-1727)
• Supposedly saw an apple fall to the ground
• He then understood that gravity was universal,
meaning it affected both the planets and us on
Earth
• Came up with 3 Laws of Motion
Force
• Force – anything that can cause a body to change
velocity
Newton’s
st
1
Law
• In the absence of a net (overall) force acting upon
it, an object moves with a constant velocity
• An object at rest remains at rest
• An object in motion tends to remain in motion
unless a force is acting upon it
Why do things on Earth not
remain in motion?
Why do things on Earth not
remain in motion?
• Friction
Newton’s
•
•
•
•
•
•
nd
2
Law
Force = mass x acceleration
Units of Force kgm/s2 = newton
So much do you weigh
Say your mass is 100 kg
F = 100 kg x 9.8 m/s2
F = 980 Newtons
Newton’s
rd
3
Law
• For any force, there is an equal and opposite
reaction force
• Gravity is holding you on the ground
• The ground is also pushing back up on you with
the same amount of force
http://www.vshiksha.com/system/files/u1/pslvc6-rocket.jpg
Newton’s Universal Law of Gravitation
• Every mass attracts every other mass through the
force called gravity
• Newton came up with this formula
F = G M1 M2
r2
M1, M2 are the masses of the two objects
r is the distance between the objects
G = constant = 6.67 x 10-11 m3/(kgs2)
So what should you know
about this formula
F = G M 1 M2
r2
• The force of attraction between any two objects is
directly proportional to the product of their masses
• The force of attraction between two objects decreases
with the square of the distance between their centers
• G is a very small number
What is the attraction of two people in
this room?
F = G M1 M2
r2
•
•
•
•
•
Say their masses are both 100 kg
Their distances are 10 meters apart
F = 6.67 x 10-11 m3/(kgs2) * 100*100 kg2/(10*10 m2)
F = 6.67 x 10-9 N = 0.0000000067 N
Remember the person weighs 980 N
Any Questions?