An official website of the United States government
Here's how you know
Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Friction coefficient between the fingertip and rubber hoses (up) and between the fingertip and aluminum (down) for three different normal force (four rubber hoses and subject pooled)