So on the Unit 2 Major Concepts sheet I don't understand:
-2.7
Can you find the displacement of an object moving with constant acceleration from a velocity time graph?
-2.7.2
Can you apply the model for constant acceleration (2.12) to determine the displacement of an object?
-2.8
Do you understand how our methods can be extended to deal with objects with non uniform acceleration?
Thanks so much!
Alexis
4 comments:
Hey Alexis,
I think I know the answers to some of your questions.
2.7 - To find the displacement of a object moving with constant acceleration from a velocity vs. time graph, you just have to find the area between the line and the time axis. Also the picture on the top of p. 13 (2.17) is really helpful in showing this
2.8 - When dealing with non-uniform acceleration you can use the same method of finding the area but you have to estimate. This is because the acceleration is changing and you cannot find the exact area.
2.7.2 - I'm not really sure on this one but I know that in an acceleration vs. time graph the area is equal to the change in velocity.
If you're still confused it might help to go back and read 2.7 and 2.8.
Hope this helps!
Sana
2.7- an object with constant acceleration on a velocity vs. time graph looks like a horizontal line. The area (delta v times delta t) from the origin to the line gets you the displacement for the time interval.
2.72- not quite sure what it asks (but Sana's looks good)
2.8- just like w/ the position vs. time^2 makes a linear graph, an acceleration vs. time^2 graph will make the non-linear graph straight. You can try it on Excel - i think.
Thanks sooo much!! This helped a lot.
you guys rock. In fact, you rock so much, you deserve a propsicle, and guess what I found on google:
http://www.doink.com/clips/SpookyChik/23888
Gaston and Sana are right here.
2.7.2 is asking if you can use the model, which is the function
x(t)=x0+(v0)t+1/2at^2 to find the displacement of an object (basically, you find the position at two times and find the change in position). You can also do this finding the area under a graph, exactly as gaston and sana said.
2.8, we haven't talked about this yet, but we'll do this tomorrow. When acceleration isn't constant, you can't really find the area in the a vs t graph using triangles and rectangles, but if you use small enough time intervals, you can use very tall rectangles (like what is shown in fig 2.22) to find the area which is equal to the change in velocity. This is the key to modeling the motion of all sorts of crazy stuff like rocketships and bumblebees.
Nice job. I am very impressed by how this class really is becoming a scientific community so quickly.
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