Warmup

1. Warmup Please complete a scatterplot for the data.

2. Warmup From test corrections on the original gravity test or from reviewing relevant chapters for vocabulary and concepts, what questions do you have before the retake?

3. Finals Review Plan

4. Scientific Outcomes Hypothesis – A testable statement which shows a cause and effect relationship. “If _, then _,” or “_ because _.” ex: the existence of the graviton as a force-mediating particle Law – A clearly defined mathematical relationship which describes a natural phenomenon and has significant evidence to support it. It has predictive value. ex: Universal Law of Gravitation, F = -G m m /r2 Theory – A statement which explains why and how things occur, and is often related to a Law or Model. It has predictive value, and significant evidence to support it. ex: General Theory of Relativity (Gravity curves space-time)

5. Scientific Method Basics Independent variable – the cause – we change it around ex: How much we make the spider move. Dependent variable – the effect – we measure what happens ex: The percent chance my cat will eat it. Controlled variables – everything else stays the same. ex: Object size, object appearance, object smell, time of day hungriness of cat, room lighting, how long the cat sees it.

6. Do people who watch too much tv really have mushy brains?Identify the dependent variable. • age of subject • TV amount • mushiness of brains • commercial break frequency • zombie appetite • none of the above

7. If you eat more chocolate, then you will get more acne. • IV: Acne DV: Chocolate CV: Age, Gender • IV: Age, Chocolate DV: Gender CV: Acne • IV: Chocolate DV: Acne CV: Age, Gender • IV: Hormones DV: Teens CV: ProActiv Cream • IV: Oils DV: Acne CV: Age, Gender, Treatment, Facewashing, Sun exposure • None of the above

8. How many mealworms does it take to make Zuldjian stink up the room a day later?Identify the Independent Variable. • Mealworms • Heat • Time delay • Stink • All of the above • None of the above

9. Scientific Method Procedure Elements Baseline – A set of measurements taken before the IV is applied, to understand the normal value for future comparison. ex: Mike got 5 headaches a month before he started taking medicine Control Group – A group which does not receive the IV, for comparison during the experiment. Identifies the presence of environmental factors. ex: …but the people who weren’t getting medicine also got better in July. Placebo – Fools researchers, test subjects, or both to eliminate or reveal sources of bias. ex: The coke/pepsi tasters didn’t know the labels were switched. Reversal – Return to baseline, to help prove cause-and-effect. ex: When the old tires were put back on, Jimmy once again crashed.

10. Before dropping any eggs onto different pillows, Joe first dropped an egg directly onto the concrete and measured the splatter radius. This is a: • Baseline • Control group • Placebo • Reversal • More than one option

11. A baseball player claimed his home run rate was skill and not his special ‘training regimen’. Later, when he was forced by a Congressional committee to stop the regimen, his home run rate dropped. This is an effective example of a: • Baseline • Control group • Placebo • Reversal • More than one option

12. Data Analysis Multiple Trials – Repeating a measurement using the same independent variable. ex: Sonia grew three plants with 1 cup of water, three with 2 cups… Precision (using Standard Deviation) – A small margin of this type demonstrates consistency, meaning low random error. ex: By being very careful, data from Joe’s second and third trials matched his first trial with minimal deviation. Accuracy – A small margin of this type demonstrates an overall value close to the correct value, meaning low systematic error. ex: Low accuracy occurred as a result of an un-calibrated scale. The overall answer was 5g too high. Best-fit lines, equations, and error bars – Helpful analytic tools for use with scatterplots.

13. What could you say about the accuracy and precision of the following data, where the accepted value is 4.3:(6.0, 6.1, 5.9, 5.8, 6.2) • Precision: ±.2 Accuracy: ±3 • Precision: ±.2 Accuracy: ±1.7 • Precision: ±.5 Accuracy: ±2 • Precision: ±.2 Accuracy: ±1.5

14. What could you say about the accuracy and precision of the following data, where the accepted value is 9.0:(9.8, 8.1, 9.1, 8.7, 9.3) • Precision: ±.2 Accuracy: ±0 • Precision: ±.9 Accuracy: ±1 • Precision: ±.9 Accuracy: ±0 • Precision: ±0 Accuracy: ±.9

15. Linear Motion Velocity Speed Distance Displacement Acceleration Scalar Vector

16. Vector: Graphical Representation The way to draw a vector is a line with a certain length, in a certain direction, with an arrow to show which way it faces. Ex:

17. How would you add these vectors?2 m/s right5 m/s left • 7 m/s right • 7 m/s left • 5 m/s right • 5 m/s left • 3 m/s right • 3 m/s left • 2 m/s right • 2 m/s left

18. Which answer choices describes a 4 mile distance? • 10 mi East, 6 mi West • 20 mi North, 17 mi South, 1 mi East • 2 mi East, 2 mi West • 5 mi East, 1 mi West

19. Which of these numbers is a speed? • 15 meters • 22 meters/second • 25 m/s2 • 10 miles • 10 miles/hour • 10 mph/s

20. Practice Problems • 1) v0=10 m/s a=-2 m/s2 t= 4 s v= ? m/s • 2) v0=1 m/s a=0 m/s2 t= 10 s v= ? m/s • 3) d0=100 m v0= 10 m/s a= -10m/s2 t= 2 s d=? m • 4) d0=0 m v0= 0 m/s a= 2 m/s2 t= 5 s d=? m

21. Practice Problems • 5) A car is initially stopped. The driver pushes on the gas pedal and it begins to accelerate. After 5 seconds, it is travelling at 60mph. What was the average rate of acceleration? • 6) Acceleration due to gravity is 10 m/s2 near the surface of the Earth. If you were to jump out of an airplane, after 1 second what would your velocity be? After 2 seconds? After 10 seconds?

22. Practice Problems • 7) A rabbit has a speed of 5 m/s, and has a 100m head-start. A dog has a constant speed of 6 m/s in the same direction. Will the dog be able to catch the rabbit in 10 seconds? • 8) A trip to Los Angeles is about 600 miles. A car averages 60 mph. A plane averages 400 mph. A high-speed rail averages 80 mph. How long does it take each of these modes of transportation to complete the trip?

23. Practice Problems • 9) If a runner travels 400m in 60 seconds around a circular track (one lap), what is their average speed and velocity? If a cheetah travels the same distance in 20 seconds, what is their average speed and velocity? • 10) A person ties a string to a can of water and swings it at a constant speed in a circle. Describe the acceleration the can is experiencing in as much detail as possible. (Not a math problem)

24. Practice Problem • 11) One train leaves travelling at an average velocity of 60mph East, and another one leaves travelling 30mph West. After 2.5 hours, what is their displacement in relation to the station? What is their displacement in relation to each other? • 12) A hang glider descends a total of 150m and then climbs back up 50m. It takes a total of 25 seconds to do this. In m/s, what is the average speed? What is the average velocity?

25. Practice Problems • 13) A hero is rocket-packing towards a closing door at a speed of 20 m/s. The door is 200 m away and will close in 5 seconds. Does the hero make it through? • Algebra II • 13b) What is the minimum acceleration the hero should use to make it through successfully?

26. Side-by-Side Comparison d d = constant v = constant a = constant d a d v a Constant t v v Zero Linear Linear Non-Linear Constant t t t t t Constant a t Zero t Zero t

27. Practice Problems v t For the graph above, draw the equivalent displacement and acceleration graphs (assuming it starts at d0 = 0).

28. Solution v d t a t t

29. Energy, Work, and Power Energy is the ability to cause change, and is measured in Joules (J). Law of Conservation of Energy - Energy can be transferred from object to object, and can change form, but never just disappears. Kinetic Energy – Large-scale motion. (Joules) KE = ½ m v2 Potential Energy – Based on position and a force. (Joules) PE = m g h Work – A transfer of one kind of energy to another. (Joules) W = F d Power – How quickly the work is done. (Watts) P = W/t

30. Momentum and Impulse p = m*v ∆p = F*t Conservation of momentum: the total momentum of the system is the same, both before and after any event. Elastic collisions: objects bounce perfectly Inelastic collisions: objects deform, stick together, and/or bounce imperfectly Momentum is conserved: the total momentum of all objects before a collision is the same as after the collision.

31. 1) A hydro-electric dam has water fall through a turbine to generate electricity. Find the force of gravity on 1 kg of water. How many joules would this produce if the turbine is pulled 10 meters at a time? • 100 W • 1000 W • 10 W • 100 J • 1000 J • 10 J

32. 2) A person on a bicycle has a downward force of 1000 N. They coast 2500 m along a flat road. How much work is done? • 2500000 J • 2.5 J • 1500 N • 3500 J • None of the above

33. 3) A lightbulb uses 60W. A battery stores 6000 J. For how many seconds can the battery power the lightbulb? • 360000 s • 100 s • 1000 s • Cannot be determined • None of the above

34. 4) A motor boat’s engine uses 5,000 J of energy in only 4 seconds. How powerful is it? • 20,000 W • 1250 W • 5004 W • 4996 W • None of the above

35. 8) Wiley Coyote accidentally steps off of a 2000 m tall cliff. He has a mass of 10 kg. How fast will he be going when he hits the ground? • 200,000J • 20J • 200 m/s • 40,000 m/s • None of the above

36. 9) A shopping cart starts at rest and rolls down a hill, picking up speed. At the bottom, it is going 4 m/s. How tall was the hill?(You do not need to know the mass of the shopping cart to solve this. Set it up and see why.) • 0.4 m • 0.8 m • 40 m • 80 m • None of the above