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1、Motion in One Dimension,Key Terminology,Distance SpeedTime*These are all scalar quantities-only magnitude,DisplacementVelocityAcceleration*These are all vector quantities-magnitude and direction,Distance vs.Displacement,DISTANCE,Total traveledPath dependentScalar quantity Both use the same variable
2、and unitsVariable:d(sometimes:x,r,)Units:m,DISPLACEMENT,Change in positionPath independentVector quantity,Check your understanding,An odometer in your car shows:Distance,Example,The following is a list of gains and loses of a Bears possession First down:gain 8 yardsPenalty lose 10 yardsSecond down:g
3、ain 11 yardsThird down:lose 1 yard,What is the total distance?What is the total displacement?,Speed vs.Velocity,DIFFERENCES,Speed:how fast(scalar)Always positiveExample:25 m/sVelocity:how fast in a certain direction(vector)Can be positive or negativeExample:25 m/s North,SIMILARITIES,Variable:vUnits:
4、m/s,Check your Understanding,A speedometer in your car shows:Speed,Check your understanding,Jim travels from Palatine to Chicago at 65 mph.Susie travels from Chicago to Palatine at 65 mph.Are the velocities equal?No,different directions,First Equation!,v=(df-di)/(tf-ti)OR commonly written asv=d/t*me
5、ans change,Average Speed/Velocity,Sample Problem,In gym,you have to run the 100 m dash.If you run it in 18 s,what was your velocity?,Sample Problem,A freaky fast Jimmy Johns delivery man makes a delivery that is 2.2 miles away and it takes him 9 min.What is his average velocity in mi/hr?,Technical d
6、ifference between calculating speed and velocity:,SPEED(AVERAGE),Total distance traveled divided by the total time elapsed*Example:Round trip drive to school,VELOCITY,Total displacement divided by total time,A change in velocity Vector quantity Positive vs.Negative Acceleration+velocity and+accelera
7、tion=_+velocity and-acceleration=_-velocity and-acceleration=_-velocity and+acceleration=_Variable:aUnits:m/s/s or m/s2,Equation:a=(vf-vi)/(tf-ti)OR commonly written as:a=v/t,Acceleration,Check your understanding,Name 3 ways to accelerate your car:Step on gas pedalStep on brake pedalTurn steering wh
8、eel,Sample Problem,A car accelerates from a stop sign up to a speed of 11 m/s.If it takes 4 to do so,what is the cars acceleration?,Velocity and Acceleration Sample Problems,Problem 1:How long does it take a turtle to travel 1,000 m if it can travel at a pace of 1.3 m/s?,Problems 2:What is the chang
9、e in velocity if an object accelerates at 2 m/s2 for 4.5 seconds?If the object started at 3 m/s,what is its final speed?,Motion Graphs,DISTANCE VS.TIME GRAPHS,VELOCITY VS.TIME GRAPHS,Slope is accelerationSlope=rise/run=velocity/time=ACCELERATION Area under graph is distance traveledArea=base*height=
10、velocity*time=Distance,Slope is velocitySlope=rise/run=distance/time=Velocity,General Graph Trends,Straight Lines CONSTANTCurving Lines CHANGINGFlat Line-ZEROSteeper the slope,the higher the value,What can you tell me about acceleration on these graphs?,Big 5 Equations,Definition of average velocity
11、:(vi+vf)/2Distance=rate*time:d=vavg*tDefinition of acceleration(final velocity):vf=vi+atTimeless:vf2=vi2+2adPosition:d=vit+1/2at2,Checklist for Success,Problem Solving Strategies,Identify givensLook for hidden givensIdentify unknown(s)Compare givens and unknowns to equationsIn the beginning:chartRe-
12、read problem if stuck*always show your work(G.U.E.S.S.),Sample Problem,What is Starlin Castros acceleration as he runs toward first base if he reaches the base with a speed of 6.5 m/s?The distance between the plates is 27.432 meters.,Sample Problem#2,An airplane can accelerate at a rate of 4.9m/s2.I
13、f it takes 45 s for the plane to start to elevate and the plane starts from rest,what is the minimum length of runway required?,Stopping Distance Sample,Seeing a stop sign ahead,a person begins to brake as they drive lawfully on Cunningham.If their reaction time is 1 s,what is the total distance they need to stop if they can accelerate at-8 m/s2?,谢谢你的阅读,知识就是财富丰富你的人生,END,
