Arduino linear actuator control

Hi every one, first off Id like to say I have just recently found Arduino and its like a whole new world was opened to me. this is absolutely great! I am most likely getting ahead of myself as I am so new but that's just me. I would like to be able to build a sorting machine using a push button triggering a 12 volt linear actuator. Imagine a chute at a 30 degree angle, with a hinged linear actuator connected to a bumper that would push material to another chute. I would like the actuator to be able to extend and retract the bumper very quickly due to the flow rate of material. So far I think I have basically confused myself with all the reading. What I have learned I think? I will need a 12 volt power source for the linear actuator. I will also need an h bridge or motor shield to do this. I have purchased a linear actuator that I already know will not work for the speed I need. I will hopefully be ordering one on advice from the forum. I also have arduino uno and seeedstudios motor shield v2.0. which at this point I am confused and do not know if the motor shield I have will work for this application. I will be greatful for any advice and thank you for your time!

You might be able to modify a windshield wiper motor to push fairly light objects.

Thank you for the response, I should of included a weight in my post. 75-150 lbs should be enough for the application.

Firgelli have an amazing range of those things.... trouble is they're industrial strength at industrial prices.

One of their ranges, the -R ones, work as servos, so no h-bridges and shields required: just use the Arduino servo write commands.

Linear actuators are usually a lead-screw arrangement so not fast, and often high friction.

Some arrangement with less gearing down will give faster motion (but with less force for the same power).

But as usual the first thing to do is a rough calculation of the power required, since force x speed = power, this shouldn't be hard. What range of motion, speed and force are invoved?