This episode is sponsored by Audible. Try Audible: http://audible.com/crashcourse Why is it hard to move a heavy bookcase across a carpeted floor? And why is it easier to keep it moving than it was to get it started moving? You might think it's all about weight, but actually it's about friction. Two kinds of friction! In today's episode of Crash Course Physics, Shini Somara tells us about Static and Kinetic friction; how they work and how they're different. *** Produced in collaboration with PBS Digital Studios: null Crash Course is on Patreon! You can support us directly by signing up at http://www.patreon.com/crashcourse Thanks to the following Patrons for their generous monthly contributions that help keep Crash Course free for everyone forever: Mark, Eric Kitchen, Jessica Wode, Jeffrey Thompson, Steve Marshall, Moritz Schmidt, Robert Kunz, Tim Curwick, Jason A Saslow, SR Foxley, Elliot Beter, Jacob Ash, Christian, Jan Schmid, Jirat, Christy Huddleston, Daniel Baulig, Chris Peters, Anna-Ester Volozh, Ian Dundore, Caleb Weeks -- Want to find Crash Course elsewhere on the internet? Facebook - http://www.facebook.com/YouTubeCrashC... Twitter - http://www.twitter.com/TheCrashCourse Tumblr - http://thecrashcourse.tumblr.com/ Support CrashCourse on Patreon: http://www.patreon.com/crashcourse CC Kids: null