Astronomy 101 The Solar System Tuesday, Thursday 2:30-3:45 pm Hasbrouck 20 Tom Burbine

Course Course Website: – 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 owebcthttps://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

Exam #1 Review questions are online Thursday 40 questions Multiple choice and True/False Review session: –Wednesday 6-7 pm in Hasbrouck 20

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/s 2

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

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 Isaac Newton ( )

Force Force – anything that can cause a body to change velocity

Newton’s 1 st 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?

Friction

Newton’s 2 nd Law Force = mass x acceleration Units of Force kg  m/s 2 = newton So much do you weigh Say your mass is 100 kg F = 100 kg x 9.8 m/s 2 F = 980 Newtons

Newton’s 3 rd 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

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 M 1 M 2 r 2 M 1, M 2 are the masses of the two objects r is the distance between the objects G = constant = 6.67 x m 3 /(kg  s 2 )

So what should you know about this formula F = G M 1 M 2 r 2 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 M 1 M 2 r 2 Say their masses are both 100 kg Their distances are 10 meters apart F = 6.67 x m 3 /(kg  s 2 ) * 100*100 kg 2 /(10*10 m 2 ) F = 6.67 x N = N Remember the person weighs 980 N

Any Questions?