The best way to do this is through the "Custom Motion Paths" animation.
1. First you'll need to draw your pipe and your arrows using the "Drawing"
group on the "Home" tab. If you want your arrows to start or end off of the
slide, draw them on the slide then drag them off the edge.
2. Click on the "Animations" tab and select "Custom Animation" from the
"Animations" group. The "Custom Animation" task pane will open on the right
side of your PowerPoint view.
3. Click on your arrow. On the "Custom Animation" task pane, click the
button titled "Add Effect." A drop-down menu will open.
4. Select "Motion Paths" from the four options (bottom option). Select the
type of motion that describes how you want the arrows to travel down the
pipe. An item will appear in the blank portion of the "Custom Animation" task
pane.
5. Right click on the Animation item in the task pane. Choose "Effect
Options" from the drop-down menu.
6. In the window that opens, click on the "Timing" tab. On the drop-down
menu next to "Repeat," choose the option that works best for you (I chose
"Until Next Click"). Press "Okay" once you've made your selection.
7. You'll see a demo of your effect. Check to make sure that it's what you
want.
For a continuous stream of several arrows, I would create arrow(s) until you
have the effect you want:
1. You can copy and paste the first arrow and then position it off-slide, on
top of the first. When you copy and paste it, a new animation item will be
added to the task pane.
2. Right click on it and choose "Timing." I would set the "Start" to "After
Previous" and then modify the timing on the dely until you have the effect
that you want.
I hope that works for you.
Eric Schmidt, a Microsoft employee
