DO NOW: (8/26/14) WRITE DOWN HW: Convert the following units: A) 540 cm  ________mm B) 72,000 mL  _________L C) 25 g  _________dag Write the following in scientific notation: 54,000,000 0.000837 0.000000000049 WRITE DOWN HW: Finish speed & velocity problems that we do not complete in class

Data XT Convert the following units: 250 mg = 0.250 g 476 L = 476,000 mL 20 m = 2000 cm Write the following in scientific notation. 873,000 8.73 x 10 5 270.056 2.70056 x 10 2

DO NOW: (8/24/14) Convert the following units: A) 540 cm  5400 mm B) 72,000 mL  72 L C) 25 g  2.5 dag Write the following in scientific notation: 54,000,000 5.4 x 107 0.000837 8.37 x 10-4 0.000000000049 4.9 x 10-11

OBJECTIVE for Week 3 SWBAT CALCULATE SPEED AND VELOCITY. Students will understand relationships between force, mass & motion.

Distance, Displacement, Speed, and Velocity The physics of motion is all about forces.  Forces need to act upon an object to get it moving, or to change its motion. Changes in motion won't just happen on their own. So how is all of this motion measured? Physicists use some basic terms when they look at motion. How fast an object moves, its speed or Velocity, can be influenced by forces. (Note: Even though the terms 'speed' and 'velocity' are often used at the same time, they actually have different meanings.

Questions for Consideration What is frame of reference? What is distance? How is displacement different from distance? What is speed? What is velocity? What are scalar and vector quantities?

Frame of Reference Coordinate frame within which to measure position, motion, or other properties of an object. OR... Observational frame tied to the motion of an observer.

Reference Frame Is the speed of the ball different relative to the pitcher, the truck driver, and the jet pilot? Why or why not?

Distance Distance (d) – how far an object travels. Does not depend on direction. Imagine an ant crawling along a ruler. What distance did the ant travel? d = 3 cm cm 1 2 3 4 5 6 7 8 9 10

Distance Distance does not depend on direction. Here’s our intrepid ant explorer again. Now what distance did the ant travel? d = 3 cm Does his direction change the answer? cm 1 2 3 4 5 6 7 8 9 10

Distance Distance does not depend on direction. Let’s follow the ant again. What distance did the ant walk this time? d = 7 cm (Total Distance) cm 1 2 3 4 5 6 7 8 9 10

Displacement Displacement (D) – difference between an object’s final position and its initial position. Does depend on direction. Displacement = final position – initial position In order to define displacement, we must include direction!

Displacement vs. Distance Example of distance: The ant walked 3 cm. Example of displacement: The ant walked 3 cm EAST. An object’s distance traveled and its displacement aren’t always the same!

Displacement Let’s revisit our ant, and this time we’ll find his displacement. Distance: 3 cm Displacement: +3 cm The positive gives the ant a direction! cm 1 2 3 4 5 6 7 8 9 10 + -

Displacement - + Find the distance and displacement of the ant. Distance: 7 cm Displacement: +3 cm cm 1 2 3 4 5 6 7 8 9 10 + -

Displacement vs. Distance Jordan runs around a track that is 400 meters long three times, then stops. What is the Jordan’s distance and displacement? Distance = 1200 m Displacement = 0 m Why?

Speed Speed (s) – Rate at which an object is moving. speed = distance / time s = d/t Like distance, speed does not depend on direction.

Speed 5 s 4 s 1 s 2 s 3 s A car drives 100 meters in 5 seconds. What is the car’s average speed? s = d/t s = (100 m) / (5 s) = 20 m/s 100 m 5 s 4 s 1 s 2 s 3 s

Speed A rocket is traveling at 10 km/s. How long does it take the rocket to travel 30 km?

Ways To Calculate Speed Constant speed is when you are traveling at the same rate of speed, such as 55 mph constantly on a highway. Average speed is taking the total distance traveled, and dividing by the total time it takes. Used for calculations that involve changing speed. Instantaneous speed is the speed at any one given point in time.

Average Speed Average speed is taking the total distance traveled (0 to 125 meters), and dividing by the total time (1 to 9 seconds) it takes. Average Speed = 125 meters = 15.6 m/s 8 seconds

Instantaneous Speed Instantaneous speed is speed at any given point in time. At 7 seconds, the distance is 85 meters; therefore the IS is Instantaneous Speed = 85 meters = 12.1 m/s 7 seconds

Speed A racecar is traveling at 85.0 m/s. How far does the car travel in 30.0 s?

Guided Practice A runner makes one lap around a 200 m track in a time of 25.0 s. What was the runner's average speed?

Guided Practice A runner makes one lap around a 200 m track in a time of 25.0 s. What was the runner's average speed? Answer: 8.0 m/s

Velocity Velocity is the speed of an object, but the direction is also included. It is calculated the same as speed, but you must include a direction in your answer. Example: Cam Newton throws the football 40 mph toward the north field goal.

Velocity Velocity (v) – speed with direction. velocity = displacement / time v = D / t

Pulling It All Together cm 1 2 3 4 5 6 7 8 9 10 + - 4 s 5 s 3 s 1 s 2 s Back to our ant explorer! Distance traveled: 7 cm Displacement: +3 cm Average speed: (7 cm) / (5 s) = 1.4 cm/s Average velocity: (+3 cm) / (5 s) = +0.6 cm/s

Guided Practice What is the average speed of a cheetah that sprints 100 m in 4 s? How about if it sprints 50 m in 2 s?

Guided Practice What is the average speed of a cheetah that sprints 100 m in 4 s? 100 meters / 4 seconds = 25 m/s How about if it sprints 50 m in 2 s? 50 meters / 2 seconds = 25 m/s Same speed!

Velocity Problem Indicate which of the following are velocities: 125 cm/sec 30 km/h northwest 350m/sec north 520 km/h

Quiz on Tues/Weds On Everything we have covered so far! Quiz will be at beginning of class. If you are late – you must come after school to make it up on Tutorial on Tuesday. Tutorial cancelled this THURSDAY 8/28!

SILENT & INDEPENDENT Speed & Velocity worksheet 1-8