Acceleration Section 6.1 in your textbook.

Thinking questions Describe the physical sensations (feelings) that you have when you experience these changes in motion: Airplane taking off Car slowing down at a red light Driving along a circular ramp Why do you think that you feel these things?

Acceleration

Acceleration = change in velocity Object moves faster  increase in magnitude (size) of velocity Object moves slower  decrease in magnitude of velocity Object changes direction

What causes acceleration? Forces Anything that is pushing or pulling on the object No forces acting = no change in motion

Graphing Acceleration Acceleration is shown as a curve on a Position vs. Time graph The curve shows that velocity is changing The object has a larger change in position for each time interval

Acceleration on a Position vs. Time graph Describe the motion for each graph.

Acceleration on a Position vs. Time graph Increasing velocity in the positive direction Increasing velocity in the negative direction Decreasing velocity in the negative direction Decreasing velocity in the positive direction

Acceleration on a Velocity vs. Time graph

These 3 graphs all show velocity that is increasing and acceleration that is constant.

Zero Acceleration Object is not changing velocity Position-Time graph: straight line increasing or decreasing Velocity-Time graph: flat line

Direction of Acceleration Slope of a Velocity vs. Time graph gives us information about the direction of acceleration Positive acceleration: slope of a VT graph is + Negative acceleration: slope of a VT graph is -

Positive Acceleration *does not always mean speeding up What happens right here?

Negative acceleration *does not always mean slowing down What happens right here?

What other information comes from a Velocity-Time graph? Displacement! Find the area under a Velocity vs. Time graph Area of a rectangle = length x width Area of a triangle = ½ base x height

Why does finding the area give us displacement? Think about the quantities represented by “length”, “width”, “base” & “height” on a VT graph. If velocity is constant, the area is a rectangle  multiply time x velocity If velocity is changing uniformly, the area is a triangle  multiply time x velocity & divide by 2 position changed a lot at the beginning, but a little at the end, so you’re actually finding the average change in position between the initial velocity & the final velocity

Find displacement over 5 seconds

Homework Page 247: Section 6.1 Review Do questions #1-4 & #6-12 in your notebooks Next class I will check that you started

Next Class Come prepared to work with your group on the Scavenger Hunt Game I will be watching and listening to make sure that you are speaking English and working together