Do Now:

1. Do Now: • Graph the following data in a velocity-time graph. Find the acceleration. • Use a new sheet of paper and please turn in your Do Now’s from last week .

2. Kinematics the branch of classical mechanics that describes the motion of bodies (objects) and systems

3. The Big Four

4. Example #1 An airplane while in flight, accelerates from a velocity of 21.0 m/sec at a constant rate of 3.00 m/sec2 over a total of 535 meters. • Which kinematics variables are stated in this problem?  • Which kinematics equation would you use to solve this problem? • What was its final cruising velocity? 

5. Example While gliding down a steep hill, a bike rider experiences constant acceleration. After 4.50 seconds, he reaches a final velocity of 7.50 m/sec. The bike's displacement was 19.0 meters. • Which kinematics variables are stated in this problem? • How fast was the bike traveling when it first started down the hill?  • Which kinematics equation did you use to solve this problem?

6. Practice • Use the rest of class to practice doing problems from the worksheet “One-Dimensional Kinematics.” This will be due Wednesday.

7. Area under a V/T Graph • The area under the curve of a v/t graph is equal to the distance covered

8. Do Now ( 6 min) A car accelerates uniformly from rest to a final speed of 56 m/sec in 10 seconds. • How far does it travel during this period of acceleration? • What acceleration did the car experience?

9. Hypothesize: Create a hypothesis for the following question. Be sure to BACK UP YOUR RESPONSE. Question: What kind of motion results from gravity? In other words, how does gravity act on falling objects? Be sure to describe velocity, acceleration, displacement, etc. When you are done, share with your elbow partner!

10. Mini-Lab: • We will do a 10 minute mini-lab on gravity. • Your goal: Describe the motion due to gravity. • Measure the time and distance for each of the 10 trials you drop the ball. • Use the formula to solve for the acceleration!!! • When your group is finished, find the average and record your data on the class chart

11. Do Now (10/5): While gliding down a steep hill, a bike rider experiences constant acceleration. After 4.50 seconds, he reaches a final velocity of 7.50 m/sec. The bike's displacement was 19.0 meters. • Which kinematics variables are stated in this problem? • How fast was the bike traveling when it first started down the hill?

12. And the acceleration is…. 9.8 m/s2

13. The Acceleration due to Gravity • The same for every object • Bigger planets, stars, etc. have more gravity • On Earth, the absolute value is always g=9.8 m/s2 • Freefall: an object being acted on only by gravity

14. Solving Free Fall Acceleration Problems Up is positive • Use Big Four Kinematics Equations • Replace a with g • In your system, take up to be positive Down is negative – so g= - 9.8m/s2

15. Example #1 You drop a ball from a 5 m window. • What are the kinematics variables you know? • How long does it take to hit the ground? • What is the ball’s final velocity right before it hits?

16. Do Now (10/6): You drop a ball from a window. It takes 2.4 s to hit the ground. • What are the kinematics variables you know? • What is the ball’s final velocity right before it hits the ground? • What is the height of the window?

17. Maximum Height • At the objects maximum height, the velocity is 0 m/s • when asked to find the maximum height or how long it takes to reach the maximum height, vf= 0 m/s

18. Do Now (10/7): A ball is thrown straight up with a speed of 4.6 m/s. How long does the ball take to reach its maximum height? • What kinematic variables are you given? • How long does it take the ball to reach its maximum height? • What is the ball’s maximum height?

19. Collected Work: • Pass in your Do Now’s and your homework. #’s 9 and 10 on your homework will be BONUS questions – don’t worry about them!

20. Practice • Use the rest of class to practice doing problems on the worksheet “Free-Fall Acceleration.” This sheet is due Friday.

21. Do Now (10/10): A ball is thrown straight up with a speed of 30 m/s. How long does the ball take to reach its maximum height? • What kinematic variables are you given? • How long does it take the ball to reach its maximum height? • What is the ball’s maximum height?

22. Practice • Use the rest of class to practice doing problems on the Test#2 Review.” This sheet is due Thursday.

23. Do Now: You drop a ball from a 10 m window. • What are the kinematics variables you know? • How long does it take to hit the ground? • What is the ball’s final velocity right before it hits?

24. jtimson@bpi.edu

25. Do Now: • Begin working on the Pre- lab questions worksheet. If you don’t have one, raise your hand. You won’t be able to answer every question yet but some of them you can answer today. • Please take out your labs and turn them in • Keep your Kinematics worksheets – they will be due on the day of the test

26. New Unit: Forces • First Topic: Newton’s Three Laws

27. Newton’s First Law • First law: Every body remains in a state of rest or uniform motion (constant velocity) unless it is acted upon by an external unbalanced force. • Net force – sum of all the forces acting on an object

28. Newton’s Second Law • Second law: A body of massm subject to a force F undergoes an accelerationa that has the same direction as the force and a magnitude that is directly proportional to the force and inversely proportional to the mass, i.e., F = ma. • Summary: F=ma

29. Freefall acceleration: • We will do a 10 minute mini-lab on gravity. • Last week in lab we determined that gravity causes objects to accelerate when dropped. How did we know? • Your goal: find the acceleration due to gravity. • Measure the time and distance for each of the 10 trials you drop the ball. • Use the formula to solve for the acceleration!!!