1.
All physics quantities fall into one of twocategories:Scalar – a quantity that can be described with asingle number (size, magnitude). Ex. I drove 15 miles. This is the quantity known as distance
2.
Vector – a quantity that includes a number and adirection. Ex – I drove 10 miles south. This quantity is known as displacementDisplacement can be defined two ways 1) distance traveled in a particular direction 2) final location relative to a starting point
3.
Which person traveled the greatest distance?Which person had the greatest displacement?
4.
Vectors are represented by an arrow - the length represents the size or magnitude - the angle represents the direction
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Vector AdditionResultant: the term given for the final sum vector whenadding 2 or more vectors together Question: 4 cm + 5 cm = ? WRONG!!! 4 cm north + 5 cm north = ? 9 cm north 4 cm north + 5 cm south = ? 1 cm south
6.
I walk 3 blocks south, 4 blocks east and3 blocks north.a)What is my distance covered?b)What is my displacement?
7.
How does the displacement of a moving objectcompare to its distance covered? Displacement <= distance
8.
A duck walks 60 m north and then 40 meast. Using a scale of 1 cm = 10 m, drawthe displacement vectors of the duck.What is the resultant displacement?What is the angle between the resultantand north?
9.
Adding vectors – the parallelogram method also called the Tip to Tail Method
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Add two vectors:100 mi east50 mi at 45o north of eastFind the length and direction of theresultant using a ruler and protractor.
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A = 80 mi westB = 60 mi at 45o south of eastA+B=?Find the length and direction of theresultant using a ruler and protractor.
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Using the scaled vector process, find themagnitude and direction of thefollowing resultants: 1)50 m N + 30 m E + 40 m N2) 5 m E + 5 m northwest + 10 m S
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Speed – a measure of how fast something moves - the rate at which distance is covered
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Speed – a measure of how fast something moves - the rate at which distance is covered
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You drive 180 miles in 3 hours. What is youraverage speed?
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Average speed = 60 mile/hourUnit for speed in SI system ismeters/secondConvert this speed to meters/second 1 mile = 1609 m 1 hour = 3600 s
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Instantaneous speed - speedometerIs speed a scalar or vector? ScalarVelocity - speed with a direction - vector
19.
A baseball is thrown at 90 mi/hr. How longdoes it take to travel the 60.5 ft from thepitcher’s mound to home plate? (3.3 ft = 1 m)v = 40 m/sd = 18.3 mt = 0.46 sImpossible!!!
20.
A horn is sounded and the echoreturns in 4 s. How far away isthe wall?
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Car 1 goes from 0 to 60 mph in 7 secondsCar 2 goes from 0 to 60 mph in 3 secondsWhich car is faster?Acceleration - the rate of change of velocity =?
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= v f - vi v f – final velocity vi - initial velocity Car 2 vi = 0 vf = 27 m/s The SI unit for t=3s acceleration is m/s2
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Constant speed or velocity “cruise control” a=0An airplane slows from 200 m/s to 50m/s in 12 seconds. What is itsacceleration?
25.
An airplane accelerates from a standingstart at 2.5 m/s2. After 7 s,a)How fast is it moving?b)How far has it travelled?
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