Motion Motion is when the distance from one object to another is changing Distance is the entire path an object travels
How can you tell if an object is in motion? Compare the distance from one object to another and see if it is changing An object is in motion if the object changes position relative to a reference point
Distance – Time Graphs Time is plotted on the x-axis Distance is plotted on the y-axis
Body at Rest If an object is not moving, a horizontal line is shown on the graph The distance stays the same as time goes by because it is not moving
Constant Speed If an object is moving at a constant speed, it means it has the same increase in distance in a given time: –Constant motion is shown as a straight line Speed = Distance Time
Comparing Speed Both of the lines on this graph show that each object moved the same distance The steeper line indicates a larger distance moved in a given time Both lines are straight, so both speeds are constant Which runner would win the race?
Acceleration The line on this graph is curving upwards. This shows that the objects’ speed is changing as time passes This is acceleration
Constant Acceleration The graph shows that the objects velocity is increasing as time passes – it is accelerating The straight line shows that it is constant acceleration
Velocity In the first part of the graph the object is moving with constant velocity. In the second part of the graph the object is at rest (not moving). In the third part the object is again moving with constant velocity.
Summary A distance time graph tells us how far an object has moved with respect to time. –The steeper the graph, the faster the motion –A horizontal line means the object is not changing its position – it is at rest –A downward sloping line means the object is returning to the start –PodcastPodcast