1. Week 5 Day 2: Announcements Test 1 is one week from today. Test 1 notes will post on the website by tomorrow. Use the “Exam Links” Link When the notes are posted, the link will be live Essays will be graded on effort. If you did it and I can read it you get 20 points. Expects grades to show up on MA by Monday MA: vocabulary on Ch1. MC question 4 When you email me, please only use my unm email address. Using this email address with ”ASTR 101" in the subject line will make sure that I see your email promptly and will be able to respond quickly. Sending Professional/School emails Make sure the subject is relevant to what you want to discuss Include your first & last name at the end of your email message text. That way the receiver knows who they are responding to and this may help make their reply more pertinent. Email addresses do not always convey your name correctly. If we have been corresponding about an issue, please include relevant sections from past emails.

2. Timelines of the Big Names Copernicus Galileo Brahe Kepler Newton 1473-1543 1546-1601 1473-1543 1564-1642 1571-1630 1642-1727

3. Clicker Question: Why didn’t my hand get crushed by the hammer? A: My bones are actually stronger than steel. B: The lead brick has a lot of inertia C: The lead brick is very strong D: The force of gravity kept the plate from moving

4. Newton (1642-1727) Kepler's laws were basically playing with mathematical shapes and equations and seeing what worked. Newton's work based on experiments of how objects interact. His three laws of motion and law of gravity described how all objects interact with each other.

5. Newton's Zeroeth Law of Motion Objects are dumb. They do not know the past and they are not good predictors of the future. They only know what forces act on them right now.

6. Newton's First Law of Motion Every object continues in a state of rest or a state of motion with a constant speed in a straight line unless acted on by a force.

7. Newton's Second Law of Motion When a force, F, acts on an object with a mass, m, it produces an acceleration, a, equal to the force divided by the mass. a = F net m acceleration is a change in speed or a change in direction of speed.

8. Newton's Second Law of Motion Demo - Force and Acceleration with fan carts

9. Newton's Third Law of Motion To every action there is an equal and opposite reaction. Or, when one object exerts a force on a second object, the second exerts an equal and opposite force on first.

10. Newton's Third Law of Motion DEMO: CART

11. Gravitational Force on a Planet For an object of mass m at or near the surface of a planet the force of their gravitational attraction is given by: F = mg F is the gravitational force. g is the planetary "gravitational constant". Your "weight" is just the gravitational force between the Earth and you.

12. Newton's Law of Gravity For two objects of mass m 1 and m 2, separated by a distance R, the force of their gravitational attraction is given by: F = G m 1 m 2 R 2 F is the gravitational force. G is the universal "gravitational constant". An example of an "inverse-square law". Your "weight" is just the gravitational force between the Earth and you.