Lesson 2 Handout Scalars and Vectors Stick Man Physics-1 (September 12, 2020) PDF

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physics lesson Scalars and Vectors Stick Man Physics-1...

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Name: Bvea Bryka A. Bontilao Section:12- OLOA Physics Lesson 2: Scalars, Vectors, and  t Velocity and Speed Variables Name Variable Displacement or X Distance t Time v Velocity or Speed Acceleration

a

Date: 09/16/20 Score: _______  

Unit

Unit Abbreviation

Meters

m

Second Meters Per Second Meters Per Second Per Second

s m/s m/s2

How are scalars different from vectors? • A scalar in physics includes only a magnitude. A magnitude is a number and a unit. • Common Scalars and Examples • Distance: the pool is 5 meters long • Speed: the golf cart can drive 10 meters per second • Time: it takes 2 seconds • All scalars have a number and a unit but no direction • •

A vector in physics includes a magnitude (number, unit) and a direction. Common Vectors and Examples • Displacement: I walked 5 meters east • Velocity: example: I drove the golf cart 10 meters per second east • Acceleration: I sped up by 4 meters per second east every second

Distance vs. Displacement • Distance (a scalar) is a measure of how far disregarding direction traveled. • My street is 100 meters long • Displacement (a vector) is a measure of where you are from the origin, or starting point, and in what direction. • I walked along my street 100 meters east How do you calculate scalar distance? You walk 6 meters east followed by 4 meters west. What distance did you walk? Direction does not matter for distance Disregard direction and add everything up 6 meters + 4 meters = 10 Meters How do you calculate the vector displacement? You walk 6 meters east followed by 4 meters west. What is your displacement?

For the displacement vector, you turn direction into a mathematical sign and add vectors. The sign in front of the number is a placeholder for direction 6 meters east = +6 Meters 4 meters west = -4 Meters Adding Vectors (+6) + (-4) = +2 +2 meters becomes 2 meters east Answer: Your Displacement is 2 meters east Q1: A dog walks 50 m East and then 23 m West. What is its distance traveled? 50 meters + 23 meters = 73 Meters Q2: A dog walks 50 m East and then 23 m West. What is its displacement? 5O meters East = +50 Meters 23 meters West = -23 Meters =(+50) + (-23) = +27 / 27 meters East

Q3: A bird has flown 850 km South for the winter when he realizes he as to go back because it is still summer. After traveling 320 km North, what is the bird’s distance traveled? 850 km + 320 km = 1170 kilometer

Q4: A bird has flown 850 km South for the winter when he realizes he as to go back because it is still summer. After traveling 320 km North, what is the bird’s displacement? 850 km South = -850 km 320 km North = +320 km = (-850) + (+320) = -530/ 530 km to the South

Calculating Scalar Speed and Vector Velocity x stands for displacement or change in position  (Greek letter delta) means change in x = xf – xi Change in position = your final position minus your initial positon You walk from the 2-mile marker to the 7-mile marker you walked (7- 2) or 5 miles forward Q5: What is Tom’s displacement if he went from a position of 10 meters to a position of 4 meters? x = xf – xi = 4 m - 10 m = 6 meters backward

You walk 6 meters east followed by 4 meters west in 4 seconds. What is your speed?

You walk 6 meters east followed by 4 meters west in 4 seconds. What is your velocity?

Q6: What is the velocity of a plane that travels 5000 miles North followed by 10000 miles North in 20 hours? Displacement : X= 5000mi + 10000mi = 15000 Given: X = 15 000 mi t= 20 hours v=? x v t 15000mi v 20 hours v=750 mi/hr North Q7: What is the speed of a plane that travels 5000 miles North followed by 10000 miles North in 20 hours? Distance : X= 5000mi + 10000mi = 15000 Given: X = 15 000 mi t= 20 hours v=? x v t 15000mi v 20 hours v=750 mi/hr Instantaneous vs. Average Velocity • Instantaneous velocity is the velocity at an exact moment • Average velocity is the velocity averaged for a whole trip Average velocity when given multiple distances with times Sally walks 5 meters east in 2 seconds, Stops for 10 seconds, then walks an additional 10 meters east in 3 seconds. What is her average velocity?

Q8: June moves 5.0 meters South in 3.0 seconds, then continues south 3.0 meters for 3.0 seconds, and finally turns and walks an 10.0 meters North in 5.0 seconds. What is her average velocity? Total displacement : (-5.0) + (-3.0) + (10.0)= 2 meters Total time : 3.0 + 3.0 + 5.0 = 11 seconds x=2m North t=11s v=? x v t 2mNorth v 11s v=0.18 m/s North

Solving for other than v How much time does it take to go 500 meters at a speed of 20 m/s? x= 500 v= 20m/s t= ? x t v 500 m t 20 m / s time = 25s

Practice Problems Thomas, on his lunch break, took 30 minutes to go to the library and then the cafe. (Look at the picture for measurements) 1) What distance did Thomas travel during lunch? 100 meters + 30 meters = 130 meters 2) What was his displacement? 100 m north = +100 m 45 m north = +45 m = (+100 m) + (+45 m) = +145m +145 meters/ 145 meters north

3) Determine the speed of Thomas during the 30 minute (1800 seconds) lunch? Distance: 100 meters + 45 meters = 145 meters x = 145 m t = 30 min or 1,800 s v=? In minutes: In seconds: x x v v t t v 

145 m 30 miN

 t 潃潬䙲湯 Ȁ࢓

v 

145 m 1800 s

 t 潬䙲 Ȁh

4) What was the velocity of Thomas during the 30 minutes? Displacement:(+100)m + (+ 45)m = 145 meters x = 145 m t = 30 min or 1,800 s v=? In minutes: In seconds: x x v v t t v 

145 m 30 miN

 t 潃潬䙲湯 Ȁ࢓ North

v 

145 m 1800 s

 t 潬䙲 Ȁh North

5) What it the direction of 15 meters North? - North 6) What it the unit of 15 meters North? - Meters 7) What it the magnitude of 15 meters North? - 15 meters 8) What is your displacement after going 10 meters East followed by 20 meters West in 10 seconds? 10 m east = +10 m 20 m west = -20 m Adding Vectors: (+10) + (-20) = -10 -10 meters /10 meters west

9) What is your average velocity after going 10 meters east followed by 20 meters west in 10 seconds? Displacement: (+10) + (-20) = 10 m west Total time: 10 s x = 10 m west t = 10 s

v=? x t 10mWest v 10 s v= 1 m/s West v

10) What is your average speed after going 10 meters East followed by 20 meters West in 10 seconds? Distance: 10 meters + 20 meters = 30 meters x = 30 m t = 10 s v=? x v t 30m v 10s  t 湯 Ȁh

11) 15 m/s is a scalar speed . (Pick from the list )

12) 15 m east is a vector displacement. (Pick from the list )

13) What is your displacement after going 10 meters east followed by 3 meter west? 10 m east = +10 3 m west = -3 (+10 m) + (-3 m) = +7 m +7 meters / 7 meters East

14) What is your distance after going 10 meters East followed by 3 meter West? 10 meters + 3 meters = 13 meters 15) Sam takes 500 seconds to travel 300 meters from home to work. During this trip, he stops at a red light and his speedometer reads 0 m/s. What is Sam’s instantaneous speed at the red light? Answer: Sam’s instantaneous speed at the red light is 0 m/s....