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