Register to reply

Bent notebook page vs a pen

by lendav_rott
Tags: bent, notebook, observations, strange
Share this thread:
Jan6-14, 08:04 AM
P: 223
I have a A4 sized notebook and every time I work on something, a corner of the page gets bent up - as I roll my pen on it I notice that if I don't roll it fast enough, it won't roll off the notebook, it reaches the top part of the bent part of the page and then comes to a halt and rolls back down.

Normally this would be a ball in a bowl problem, but the bowl's surface is solid and doesn't change. The bent page, however, does.

What is the force that the bent page counteracts the approaching pen with? The page is bent up, but as the pen rolls on it, it starts to bend back down, but if the pen isn't rolling fast enough, the page bends itself back up and pushes the pen back.

How does this work?
Phys.Org News Partner Physics news on
Engineers develop new sensor to detect tiny individual nanoparticles
Tiny particles have big potential in debate over nuclear proliferation
Ray tracing and beyond
Simon Bridge
Jan6-14, 09:11 AM
Sci Advisor
HW Helper
Simon Bridge's Avatar
P: 12,974
It's a spring.
Jan6-14, 09:28 AM
P: 3,002
The page curls because one side has absorbed more moisture than the other side (or one side has lost more moisture). The side with more expands causing the paper to curl.

The curled page then has a little springiness to it so as the pen rolls on it the paper gives and the pen slows its roll and then it pushes the pen back. If the pen rolls faster then it overcomes the springiness and rolls off and the paper springs back.

Register to reply

Related Discussions
Best notebook to run Pro/E Mechanical Engineering 6
What is out of the page and into the page mean in magentic field? Introductory Physics Homework 13
Charge movement in a magnetic field along the z-axis (into page/out of page) Introductory Physics Homework 16
A really big huge notebook! Computing & Technology 17
My Notebook Computing & Technology 4