How powerful is an elephant trunk if it swiped a human, a lion, hippo, or an African bull?
Q: How powerful is an elephant’s trunk?
Google images is a treacherous place when it comes to this kind of topic, and the page is full of photoshop jobs that make even my own MS Paint efforts look exceptionally realistic.
There are a few diamonds in the rough, though.
This is not one of them.
OK, here’s a real one, with an elephant demonstrating its trunk strength on the heaviest of those animals mentioned in the question, the hippo:
It was at that point, Mrs Hippo knew she had f*cked up.
Apparently the bull elephant was offended by a group of hippos grazing too close to him, and became agitated. The mother hippo, to give her due props, stood her ground, but the encounter went predictably badly.
That hippo is probably close to 1.5 tonnes, so we know that the other animals, being much smaller and lighter, would fare even worse.
To add insult to injury, the hippo was bullied afterwards. (The elephant continued to be an arsehole.)
The mother and the calf were quickly reunited but far from being lavished with sympathy, the herd acted aggressively towards her and she was forced to retreat with her calf and stand apart from the group.
The elephant’s mood did not improve much, as he carried out a handful of mock charges on other hippos before venturing into the waterhole to chase away a few sunbathing crocodiles. 
It’s not looking too great for the others, then.
This is a real photograph, too, although it’s incorrectly used as an example of trunk strength, because the elephant is using her (yes, it’s a female) tusks to impale the buffalo. If you look closely you can see a tusk that’s bursting out of the other side of the soon-to-be ex buffalo/beef kebab.
The woman who took the video confirmed that the elephant used its tusks. But since buffalo are comfortably lighter than hippos, we know an elephant could send a UMO (unidentified mooing object) into orbit with its trunk, if it so wished.*
Lions? Large ones only weigh a couple of hundred kilograms. We can extrapolate that an elephant could send a UMO (unidentified meowing object) into orbit.
Humans? Most of us are comfortably lighter than a lion, so I think we all know where this is going.
Let’s revert to trusty MS Paint for an artist’s impression:
I’ve helpfully labelled the diagram to give you an idea of what’s occurring. It doesn’t end well for the human. (Hint: looks like someone’s going into orbit.)