Difference between Average Speed & Average Velocity in VelocityTime graphs?
I just want to know what is the difference on how to find Average velocity and Average speed when I try to find it in VelocityTime graphs
Also how do you find distance traveled and displacement in these velocitytime graphs. Thanks in advance for your help. Please use fairly simple formulas cause I am in highschool and haven't learned calculus and other physics equations. I know displacement is something to do with finding area. 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
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If we deal with straight line motion, we often label the directions positive and negative, though North, East, South, West, Up and down are other possible names for the directions. If you positve velocity, you are heading in the positive direction. Mere velocity doesn't say where you are however  as in positive position or negative position. If you read this response on the same computer as you posted your query, there is every possibility you are now back in the same place. That means your displacement between posting and reading is zero, though you may have travelled a great distance during that time. The area under a speed time graph gives the distance covered. Note that speed is never negative. It is never positive either. It simply doesn't have direction at all  just magnitude. If you have a velocity time graph, that graph can dip below the horizontal axis. That is because velocity also has direction, and can be in the positive or negative direction. When we say the area under a velocity time graph, we actually mean the are between the velocity time graph and the horizontal [time] axis. Sections above the axis have positive area, areas below the axis have negative area. When we add all the areas together, there is always a chance that the positive and negative parts may cancel out. This means the object has returned to its original position. To get distance from a velocity time graph, we find the area between each section and the time axis, ignoring the sign of the area  you just look at the magnitude. has that answered everything? 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
2 Attachment(s)
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http://www.physicsforums.com/attachm...1&d=1316969322 http://www.physicsforums.com/attachm...1&d=1316969322 How would I find distance traveled, displacement, speed and velocity from these graphs? I would appreciate it if you could show your work. Thanks in advance. 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
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In the first case this divides the whole thing into a series of triangles and rectangles, which are easy to find the area of. In Part 1 Sections A,B & C are above the time axis, so represent positive areas for displacement. Sections D, E & F are below the axis, so represent negative areas for displacement. Lets pretend the areas under A,B&C was 200, and the Areas fro section D,E&F was 300 That would represent a total displacement of 300, but a distance covered of 500 Since the time was 720 seconds, that would mean average velocity = 100/720 while the average speed would be 500/720 Similar working for part 2 except you have to estimate some areas as the bounding line in some cases is a curve. If you know the equation of the curve, you could use integration but in physics we usually use either a "counting the squares" technique, or approximate to triangles/rectangles. 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
hey just wanted to ask a question related to this ...suppose the entire graph is above the horizontal axis so the distance and the displacement will be the same??

Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
i short yes
u can also think like this.... suppose a body moving with velocity v in right direction Considering the velocity in right direction to be +ve and plotting graph, u can say that when velocity becomes 0 at any instant, i means that the body has stopped moving right. Again as velocity becomes ve we can say that body is moving left now for displacement if u consider right direction to be +ve u must consider left direction to be ve... so u can find the area under vt graph (the area enclosed above +ve axis would give displacement in right direction and area under the +ve x axis would give displacement in left direction) now add the displacements(with proper signs) to get net final displacement from initial point now speed dosent consider direction so when body starts moving left, graph would still go up) here sum of areas of graphs will give us the distance traveled if the entire graph is above the horizontal axis so the distance and the displacement will be the same as there is no displacement along the opposite direction NOTE:velocity dosent have to be along left and right it can be up and down or some other any way 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
thnku :)

Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
one more question...i am given a stair case shaped velocity time graphy above the xaxis with decreasing velocity and i am asked to find instantaneous velocity...should draw tangent at any corner of the stair case and find the slope or what shoud i do i am confused!

Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
if u are given a velocity time graph then u should be able to find instantaneous velocity
by locating the velocity co ordinate for the corresponding time co ordinate 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
u mean if i have points (1,3) (2,2) (3,1) (4,0) then instantaneous velocity at time 1 would be 3 ??

Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
if it is velocity time graph with time in x axis, then i think yes
instantaneous velocity means velocity at any instant of time 
Re: Difference between Average Speed & Average Velocity in VelocityTime graphs?
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If you are considering tangents, you are thinking of ways to get the instantaneous velocity from a positiontime graph. 
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