Ch. 11 Sec. 2Ch. 11 Sec. 2
Speed & VelocitySpeed & Velocity
SpeedSpeedRatio of the distance traveled in an Ratio of the distance traveled in an amount of timeamount of time
Speed = distance/timeSpeed = distance/time
Units: km/hr, m/sec. Units: km/hr, m/sec.
SpeedSpeed
Average SpeedAverage Speed– Total distance traveled divided by the timeTotal distance traveled divided by the time– Velocity (v) = Distance (d)/Time (t)Velocity (v) = Distance (d)/Time (t)
Instantaneous SpeedInstantaneous Speed– Rate at which an object is moving @ given Rate at which an object is moving @ given
momentmoment– Car SpeedometerCar Speedometer
Speed ProblemsSpeed ProblemsSpeed ProblemsSpeed Problems
What is the speed of a cyclist who travels 50 meters in 25 seconds?
S = d/t
You are in a car traveling an average speed of 60 km/hr. The total trip is 240 km. How long does the trip take?
t = d/s
50 m/25 s
2 m/s
240 km/60 km/hr
4 hrs.
MotionMotion
Represented by a distance-time Represented by a distance-time graph.graph.– The slope is the speedThe slope is the speed
Speed in a given Speed in a given direction. direction.
Uses: Navigation Uses: Navigation (airplanes, ships), (airplanes, ships), weather, etc.weather, etc.
Vector quantity – Vector quantity – represented graphically represented graphically by arrows ( ).by arrows ( ).– Length = magnitudeLength = magnitude– Arrowhead = Arrowhead =
directiondirection
VelocityVelocityVelocityVelocity
If you row a boat upstream at 10 If you row a boat upstream at 10 km/hr and the river has a km/hr and the river has a downstream velocity of 5 km/hr, you downstream velocity of 5 km/hr, you are actually moving at what velocity?are actually moving at what velocity?
Velocity ProblemVelocity ProblemVelocity ProblemVelocity Problem
10 km/hr upstream
5 km/hr downstream
5 km/hr upstream
=
ProblemProblem
A person runs a 100.0 meter dash is A person runs a 100.0 meter dash is 11.8 seconds, what is the velocity?11.8 seconds, what is the velocity?
VelocityVelocitySpeed and Velocity Lab