00:01
We have a velocity time graph.
00:02
So we have velocity.
00:04
Here's our time.
00:09
It goes from negative 10 to 20.
00:11
I'm not going to be able to draw the best, but we're going to do the best we can.
00:14
So it's negative.
00:15
Then it goes up, over, and then down.
00:19
And so we want to know what is the accelerations at three different times? 7 seconds, 12 seconds, and 17 seconds.
00:29
So at the 7 second mark, it is this line.
00:32
And so when we are doing acceleration, you have change in velocity over change in time.
00:38
We can see we're going to do the slope of the line because we have rise overrun.
00:41
And so you're going to pick two points.
00:43
And so i picked the zero zero point, which i saw was six seconds at zero mark.
00:50
And so that is my first.
00:55
This is not writing very well.
00:58
So we have six and zero.
01:03
And then i chose the seven second mark.
01:07
Because that was one that we were told to choose.
01:10
And at that point, it is moving at six meters per second.
01:13
You'll need to look at the exact graph to get that.
01:16
So acceleration is six minus zero, doing our ys, over our x's, seven minus six.
01:26
And we see that we get six meters per second squared.
01:29
That is our acceleration at that point.
01:31
The reason i'm able to use two different points is because it's a constant acceleration.
01:35
On the graph, it's a straight line.
01:37
For the next time, the 17 second mark, it is, excuse me, the 12 second mark, it is when it has this straight line right here.
01:46
That slope is zero.
01:47
It's moving at constant speed.
01:50
So at the 12 second mark, acceleration is zero...