1. HW Due – Web Quest AND #1-9 from the other day, have them out on your desk please HW for Tonight: Math Practice #1-8 on handout for HW…AND #19-21 p. 72 of your book Graded Who Wants to Be a Millionaire Competition next class – get ready! ***bring textbooks next class*** Do Now: 5 minutes! Take one and complete #1-2! If FALSE, correct it to make it true! Please take a clicker and put aside Objectives Today: I can interpret Newton’s 2 nd Law both conceptually and mathematically

3. Net Force = mass x acceleration F net = m a Newton’s 2 nd Law states that a Net Force applied to a mass causes a change in motion (an acceleration!) Use the following info AND the info on the board to solve your Do Now! Either write this stuff down, take a picture and re-write at home/later, or take a picture and print it out…remember, no phones on Open Notes Quizzes!

4. Balanced forces cause constant acceleration. 1.True 2.False 3.Not quite sure Balanced forces cause ZERO acceleration. OR Unbalanced forces cause acceleration.

5. The greater net force applied, the greater the acceleration. 1.True 2.False 3.Not quite sure

6. A non-zero net force (in other words, a net force MORE than 0) acting on an object causes acceleration. 1.True 2.False 3.Not quite sure

7. The forces acting on an object at rest are unbalanced. 1.True 2.False 3.Not quite sure The forces acting on an object at rest are balanced. OR The forces acting on an object changing velocity are unbalanced.

8. Force and acceleration are inversely proportional. 1.True 2.False 3.Not quite sure Force and acceleration are directly proportional.

9. Mass and acceleration are inversely proportional. 1.True 2.False 3.Not quite sure

10. If you triple the force applied to something, you would expect 1/3 as much acceleration. 1.True 2.False 3.Not quite sure If you triple the force applied to something, you would expect 3X as much acceleration.

11. F net = m a (Net Force = mass times acceleration) 1 = 1 x 1 3 = 1 x 3 NOT 3 = 1 x 1 3

12. Two shopping carts of equal mass are pushed by two different people. The first cart accelerates four times more than the second cart. Describe the magnitude or amount of force applied to the first cart compared to the second cart. 1.First cart has the same net force as the second cart. 2.First cart has 4x the net force of the second cart. 3.First cart has ¼ the net force of the second cart. 4.Not enough info

13. Two shopping carts of equal mass are pushed by two different people. The first cart accelerates four times more than the second cart. Describe the magnitude or amount of force applied to the first cart compared to the second cart. Cart 1 Cart 2 F net = m a Fnet = m a Force = 1 x 4 Force = 1 x 1 Force = 4 Force = 1 Cart 1 experiences 4x the force of cart 2!

14. EXTRA QUESTION: Two shopping carts of DIFFERENT mass are pushed by two different people with the SAME FORCE. The first cart accelerates four times MORE than the second cart. Describe the mass of the first cart compared to the second cart. 1.First cart has the same mass as the second cart. 2.First cart has 4x the mass of the second cart. 3.First cart has ¼ the mass of the second cart. 4.Not enough info

15. EXTRA QUESTION: Two shopping carts of DIFFERENT mass are pushed by two different people with the SAME FORCE. The first cart accelerates four times MORE than the second cart. Describe the mass of the first cart compared to the second cart. Cart 1 Cart 2 F net = m a 1 = m x 4 1= m x 1 m = 1 4 Cart 1 has ¼ the mass of cart 2!

16. # Net Force (N) Mass (kg) Acceleration (m/s 2 ) Use this column for work space if needed 1. 102 2. 202 3. 204 4. 25 5. 10

17. What happens if you are solving for NEWTONS (Force)…. – but are given MASS in GRAMS? (g) – Or acceleration in miles per hour per second? **Remember** F net = m. a N = kg m s 2 The Newton is an abbreviation!

18. Hw Review Take out #1-9 from last class – we are rapidly reviewing Your responsibility to check/ correct. Each slide will have solutions and will remain up for 1-2 minutes. Please check and see a teacher or peer for help. REMEMBER – It’s OK if your answers are worded differently!

19. 1. Define: Acceleration is the change in velocity over time as an equation, a = (v2-v1) / t – How it is produced: it is produced by a net force as an equation, F net = ma 2. Net force is the combination, sum of, or resultant, of all forces. Or, it is what you get when you add all the forces together. 3. Since F net = ma, doubling F means double the a. Net force and acceleration are directly proportional 4. Since F net = ma, doubling m means ½ the a. Mass and acceleration are inversely proportional

20. 5. Directly: whatever you do to one quantity, you do to the other. Ex: if one quantity halves, so does the other. If one quantity doubles, so does the other. – Inversely: increasing one quantity decreases the other by the inverse. Ex: if one quantity halves, the other doubles. If one quantity doubles, the other halves. 6. Applying a net force to a mass produces and acceleration; F = ma (or any variation of these words/equation) 7. F net = ma F net = (20,000 kg)(1 m/s 2 ) F net = 20,000 kg. m/s 2 In other words 20,000 N

21. 8.Friction is caused by surface irregularities aka ‘bumps’. It acts in the OPPOSITE direction of motion (aka opposes motion) 9. The crate moves with a CONSTANT VELOCITY. Therefore, it is not accelerating. Therefore, the net force must be 0 according to the 1 st and 2 nd laws. – 100 N of force applied – Net Force = 0 – Since net force = 0, there is zero acceleration

22. Post Lab Graded Post Lab You can choose to complete in groups of 1-4 When you are done, you will turn in for a grade. Then, you will continue working on Newton’s 2 nd Law Math CHECK IN AT STOP SIGNS! Anything not completed on Math Practice #1-8 is HW HW for Tonight: Math Practice #1-8 on handout for HW…AND #19-21 p. 72 of your book Graded Who Wants to Be a Millionaire Competition next class – get ready! ***bring textbooks next class***