[jeremyarussell]

I'm pretty sure most people know about gravity when they leave school, I'd even venture to say that most at least know of the concept that things are made up of smaller things. I'd also venture to call those two things part of "basic" physics.

[DanBC]

I'd hope so.

(http://www.falstad.com/gravity.html)

"What happens if you drop a pen on the moon?"

   If a pen is dropped on a moon, will it:
   A) Float away
   B) Float where it is
   C) Fall to the surface of the moon

This question was asked to students studying physics across a range of levels. I don't know if they just cherry picked the really bad answers. I have no idea how these US educational course translate to international courses.

> "The gravity of the moon can be said to be negligible, and also the moon's a vacuum, there is no external force on the pen. Therefore it will float where it is."

> "Gravity will not pull it down, because there is less of it. It shouldn't float away just because I've never seen it happen. There's a balance between gravity and the opposite force."

[craigvn]

I'm pretty sure most people leave high school and if you asked them 12 months later about gravity they couldn't give any kind of coherent answer, just something along the lines of "it stops us floating off into space". Just like all people need to know about coding is it is how websites and apps are made. Any more specific, no one cares.

[klodolph]

It's the bulk mail method. Send physics at two million people a year, not everyone is going to "get" it. But we don't know which of those two million are going to grow up and revolutionize the semiconductor industry, which of those are going to jury-rig some clever device at home that keeps their energy bill down, and which of them are going to forget it all.

Just like you never know which email address will respond to a Viagra advertisement.