We find out about the true nature of apple cores. They're not as innocent as they look. Plus, we ask how a ball can appear to move uphill. Like this podcast? Please help us by <a href="https://www.thenakedscientists.com/donate">supporting the Naked Scientists</a>

How can something appear to roll uphill?

Each week we set out to solve one of the world's weirdest, wackiest, funniest and funkiest scientific puzzles. And along with the answer there's a brand new question to think about for next time...