How to Make Hydraulic Powered Robotic Arm from Cardboard Slime Sam finds it hard to believe that water has great power. Drops of water are so small, what can they do? But Sue explains about hydraulics - a science that studies the properties of water and other liquids and their uses in people's life. Sam wants to see it in action. Sue tells him that even one cup of water can lift a bottle and builds an incredible robotic arm that is controlled by special levers and moves without electricity. Do y