Wonderful WednesdayWonderful Wednesday

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What is the formula for What is the formula for speed?speed?

SpeedSpeed

Speed = Distance/ TimeSpeed = Distance/ Time

Units: m/sec, m/hrUnits: m/sec, m/hr

AgendaAgenda

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Notes on speedNotes on speed

Acceleration LabAcceleration Lab

Motion Motion is a change in position measured is a change in position measured by distance and time.by distance and time.

Speed Speed tells us the rate at which an object tells us the rate at which an object moves.moves.

Velocity Velocity tells the speed and direction of a tells the speed and direction of a moving object.moving object.

Acceleration Acceleration tells us the rate speed or tells us the rate speed or direction changesdirection changes

DISTANCE-TIME GRAPHSDISTANCE-TIME GRAPHS

TimeTime is always plotted on the X-axis is always plotted on the X-axis (bottom of the graph). The further to the (bottom of the graph). The further to the right on the axis, the right on the axis, the longerlonger the time from the time from the start.the start.

DistanceDistance is plotted on the Y-axis (side of is plotted on the Y-axis (side of the graph). The higher up the graph, the the graph). The higher up the graph, the furtherfurther from the start. from the start.

Notice the x and y axes!!Notice the x and y axes!!For speed graphs this will never change!For speed graphs this will never change!

Time is Time is increasingincreasing to the right, but its to the right, but its distance distance does notdoes not change. It is not moving. change. It is not moving. We say it is We say it is At RestAt Rest..

If an object is STOPPED, a HORIZONTAL If an object is STOPPED, a HORIZONTAL line in shown.line in shown.

Time is Time is increasingincreasing to the right, and to the right, and distance is distance is increasingincreasing constantly with time. constantly with time. The object moves at a The object moves at a constant speedconstant speed..

Constant speed is shown by Constant speed is shown by straight straight lineslines on a graph on a graph..

Constant SpeedConstant Speed

A A steeper linesteeper line indicates a larger distance indicates a larger distance moved in a given time. In other words, moved in a given time. In other words, higher speedhigher speed..

Both lines are Both lines are straightstraight, so both speeds , so both speeds are are constantconstant..

A line that curves A line that curves upwardupward shows an shows an iincrease in speedncrease in speed..

In other words, in a given time, the In other words, in a given time, the distance the object moves is change distance the object moves is change (getting larger). It is (getting larger). It is acceleratingaccelerating..

Summary…Summary…

A distance-time graph tells us how far an A distance-time graph tells us how far an object has moved with time.object has moved with time.

The steeper the graph, the faster the The steeper the graph, the faster the motion.motion.

A horizontal line means the object is not A horizontal line means the object is not changing its position - it is not moving, it is changing its position - it is not moving, it is at rest.at rest.

Acceleration LabAcceleration Lab

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