I was once told by my dad that peddling a bike down a hill would actually slow you down. I wwas about 15 before i realized this wasn't true.
A childhood belief about physics

others believed things like this
- my brother told me that if i ride my bike with my mouth open i will swallow my tounge. Anon
- I used to think that if you ate cat food you would die. I found out it wasn't true
— Bob#4 - My sister just recently realized that the lyric "more than a woman" wasn't 4 letter woman!— Anne
- When i was about 5 I used to believe that Broken Hill was a broken hill. — Saad
- I use to think that there were HILL COWS!— Erin
- I used the scar on my dads leg was a shark bite when in fact he fell off his bike when he was a child— Wendy Murray