Physics: Ping Pong Ball Launcher

So for Physics we have to make a device that can launch a ping pong ball into a cup from a certain distance.

I drew it all out here...



The catch is that the only thing that can launch the ping pong ball is this flimsy rubber band and I can't let go of it on my own, it has to be triggered somehow.

I'm not exactly sure how to construct something like this as I'm not good at the technical stuff in physics, I'm just good at doing the work and I forgot we had to do something like this -_- Any advice? My A depends on whether or not it goes in the cup.

what's the width the box

Projectile?

Given either an angle or initial velocity at the moment of shooting, you can easily set the height of the projectile at any moment in time to be a function of other variables, then adjust it so that it matches the height of the cup.

Paperwork aside, I'm thinking of one of those Y-shaped thingies used for shooting birds whose name escapes me at the moment (slingshot), and by "trigger", can't you at least use a scissor to cut a string that's holding the rubber band in place? Or maybe you can do one of those car-bumps-bookshelf-book-falls-off-onto-seesaw-launching-the-cat-into-the-backyard chain reaction kind of thing.

I'd probably set up a test rig at home with the same dimensions, cause aerodynamics on the pingpong ball will definitely affect how it flies.

As for actually triggering it, you could take design cues from a mousetrap - spring is attached to a bar, which another bar latches across to lock it in place.


So when you lift the bar (due to removing the cheese) the spring is free to snap shut.

If you attach the ends of the elastic to eyehooks and stick each into pegboards, you can adjust the trajectory so the pingpong ball goes where you want it.

I'd probably set up a test rig at home with the same dimensions, cause aerodynamics on the pingpong ball will definitely affect how it flies.

As for actually triggering it, you could take design cues from a mousetrap - spring is attached to a bar, which another bar latches across to lock it in place.


So when you lift the bar (due to removing the cheese) the spring is free to snap shut.

If you attach the ends of the elastic to eyehooks and stick each into pegboards, you can adjust the trajectory so the pingpong ball goes where you want it.

Ack, I see what you're going for but I just don't see me having the time to build that... Even though it might be easy. I might consider something like this.

Projectile?

Given either an angle or initial velocity at the moment of shooting, you can easily set the height of the projectile at any moment in time to be a function of other variables, then adjust it so that it matches the height of the cup.

Paperwork aside, I'm thinking of one of those Y-shaped thingies used for shooting birds whose name escapes me at the moment (slingshot), and by "trigger", can't you at least use a scissor to cut a string that's holding the rubber band in place? Or maybe you can do one of those car-bumps-bookshelf-book-falls-off-onto-seesaw-launching-the-cat-into-the-backyard chain reaction kind of thing.

Yes, I can cut the rubber band while it's in place. That can account for something of a 'trigger'. The only act of force that can launch the ping pong ball has to be the rubber band though.

I've been considering a catapult really... The more simpler it is, the easier it'll be to test run it and perfect a specified angle to match the velocity at which the catapult will launch it at. My first prototype of the device was a pvc pipe with two incisions on each side so the rubber band can stretch back and I can put the ball inside from the top end. Kind of like a cannon, really. But by making the incisions in the pipe it contracted and wouldn't fit the ball anymore so I think I might take my chances with a catapult.

Depending on how you make them catapults can be quite inaccurate, and if it's only one rubber bandit might not be strong enough to fire. I think a slingshot with a trigger is your best bet. Maybe a crossbow? That would be awesome, a ping pong ball shooting crossbow.

I'm kind of jealous of your physics classes.

I have no idea how to go about making a crossbow.. But I did think about it.

Get a pipe a bit larger than the ball (TP rolls if they were longer would work ok, otherwise you could roll your own from card paper or just buy one), and humteen inches long. Put the band across the opening. Tie a string around it and drop that through the pipe.

Set the ball in the elastic with the string under it, pull down on the string. Since the elastic is in a V shape, the ball will be gripped on either side by it, and go down too.

Think this is about the simplest crossbow design that's elastic powered. Getting tube size closer to the ball's size should make it more accurate.