Day 1 UNIT 1 Motion Graphs x t Lyzinski Physics

PHYSICS - Mechanics - Electricity - Magnetism - Optics - Waves KINEMATICS - Mechanics A “description” of motion - Electricity DYNAMICS - Magnetism A study of what “causes” motion - Optics - Waves

Day #1 * Distance * Speed * Unit Conversions * Scalars * d-t graphs

Definition Distance (d) – the length of the path followed by an object. * If an object’s path is straight, the distance is the length of the straight line between start and finish. ** If an object’s path is NOT straight, the distance is the length of the path if you were to “straighten it out” and measure it the way you would measure the length of a curved shoelace. start finish start finish

B C -3 -2 -1 0 1 A meters Using the number line above, what would be the distance travelled if an object travelled from ….. 1m - A to B - A to C - A to C and then back to A - C to B, passing through A 4m 4m + 4m = 8m 4m + 1m = 5m

4 yd B 12 yd 5 yd C A Sally and Timmy are at point A. Sally walks directly to point C (taking the shortest path). Timmy also takes a “shortest path”, but has to stop at point B for lunch first. How much further has Timmy walked when he arrives? 4 yd

(or s=d/t) Definition Average Speed (s) – the distance travelled during a time interval divided by the elapsed time. s = d/Dt (or s=d/t) we often abbreviate ”Dt” as “t”

s = d/t  t = d/s = (7mi)/(6mi/h)=1.17h B C -3 -2 -1 0 1 A miles Larry walks from point B to point C, and then goes directly to point A. If he walks at an average speed of 6 mph, how long does the trip take him? d = 3mi + 4mi = 7mi s = 6 mi/h s = d/t  t = d/s = (7mi)/(6mi/h)=1.17h

B C -3 -2 -1 0 1 A km Larry runs from point A to point B in 5 minutes and then proceeds to jog directly to point C, taking his time in 30 additional minutes. Find… Larry’s average speed during the first portion of the trip. The average speed during the second portion of the trip. Larry’s average speed for the entire trip. s = d/t = (1km)/(5min) = 0.2 km/min = 12 km/h s = d/t = (3km)/(30min) = 0.1 km/min = 6 km/h s = d/t = (4km)/(35min) = 0.114 km/min = 6.86 km/h

Unit Conversions Convert 5 km/h to m/s. Convert 60 ft/s to mi/h. Convert 30 mi/h to m/min!!!!

Definition distance speed time Scalar – a quantity that has a magnitude only, no direction. * YES, scalars can have units. ** What scalars have we learned about thus far? ___________ ____________ ___________ distance speed time I thought time could march backward?

d-t graphs E F D C B A Constant speed Speeding UP Constant Speed (faster!) Slowing Down At rest t (sec) d (m) B C E A D F 10 15 20 27 36 120 100 50 30

sAB = rise/run = (30-0m) / (10-0s) = 3 m/s t (sec) d (m) B C E A D F 10 15 20 27 36 120 100 50 30 SLOPE Speed on a d-t graph can be found by taking the _______________. sAB = rise/run = (30-0m) / (10-0s) = 3 m/s sCD = rise/run = (100-50m) / (20-15s) = 10 m/s

1 Open to in your GREEN packet 520 – 170yd = 350 yd (approximately) d-t graphs CANNOT have sharp points NOTHING CAN STOP INSTANTANEOUSLY!! minutes 520 – 170yd = 350 yd (approximately)

HOMEWORK Check out your Unit 1 Schedule … Day #1 We will “try” to follow it night by night.