Watch Episode Friction: Crash Course Physics #6 S1 E6 / 10m 27s 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! Today, Shini tells us about Static and Kinetic friction; how they work and how they're different.