Physics of hitting a tin can target filled with water...

[Jonnyroy]

Why does a tin can (not necessarily aluminum, but heavier metal) filled with water, and is open on top, fly straight up (3 inches to 3 feet) when struck by a fairly powerful pellet??
Sure, the water inevitably shoots a spout upwards...but why does the can jump "up"? I can't quite figure out the physics involved ;-)

 

[markT]

Because it can't jump down...

 

[jarmstrong]

look at the bottom of the can,,, the force causes the water to exert pressure in every direction, simple hydraulics,,, the bottom flexes downward, then hits the ground, reacting with a jump upward

 

[rcs9250]

And to add to post #3:The water, assuming little to no air in the can, also hydraulics against the top equally but against air, so the bottom wins. As mentioned in post #2.

 

[Septicdeath]

Because you scared it.

 

[Gerry52]

Hydrostatic shock expanding in all directions

 

[superchikn]

Dunno.
Never shot a can full of water with an airgun. Now I have to go try this!

Edit: when you say fairly powerful what fpe range are you talking?

 

[Jonnyroy]

look at the bottom of the can,,, the force causes the water to exert pressure in every direction, simple hydraulics,,, the bottom flexes downward, then hits the ground, reacting with a jump upward

That helps.
My hypothesis starts with a vacuum-like void, or cavity, forming in the body for water as the pellet passes through it; thus pushing water above it to spout out of the can, and forcing water below it to compress (or more accurately, just increase in pressure). THEN, it’s the collapse of the void that pulls directly upwards on the water below it, hence pulling the can straight upwards ( because all other forces are canceling each other out.
But I’m still not very sure this is a sound idea.

 

[Jonnyroy]

Dunno.
Never shot a can full of water with an airgun. Now I have to go try this!

Edit: when you say fairly powerful what fpe range are you talking?

Say 20 ft. lbs. at 20 yards would make an obvious jump. Whereas sub 12 ft. lbs. at 50 yards may get only an inch or less of a jump.

 

[Florida_Man]

This really makes me want another 25 cal

 

[lbc_PSI]

Water does not compress well if at all..it takes humongous pressure. So when a projectile hits a can full of water that's sealed, the pressure (from hydrostatic shock..Gerry52) forces the can to split at a weak point..which creates a hole..that tuns the can into a "water rocket".

 

[Jonnyroy]

This can is jumping about 10" straight up from the dark brown bench below it. It was shot (from left to right...at a 90 degree angle to the front of the camera...from 10 yards by a GAMO Magnum GR .22 cal with JSB 18.13 pellet. The can was a 28oz. can of beans filled with water.