1. VYPT: Bouncing Drop Water droplet before, during and after impacting with a super- hydrophobic material (in this case, a nanotube-covered substrate) Image credit: Applied Physics Letters

2. What is being investigated? Investigate the motion of water droplets falling on a hydrophobic surface. Image credit: ANVER Corp. Teflon tape is highly hydrophobic

3. How can it be measured? Rebound height (vertical direction) Spread (horizontal direction) Image credit: Van Der Waals-Zeeman Institute Spread

4. What factors might affect it? Height from which water droplet is released (which affects its impact speed) Size (or volume) of water droplet (determined by type of pipette used) Type of hydrophobic surface (e.g. normal vs super hydrophobic) Temperature of water droplet Tilt angle (i.e. at what angle does the water droplet make contact with the impacting surface)

5. How might these [factors] be measured? Height – measured with ruler Size of water droplet – measure droplet diameter(?) Temperature of water droplet – allow water to reach equilibrium, then measure temperature Tilt angle – measured using a protractor(?)

6. What equipment might be needed? Retort stand, boss head and clamp Pipette, eye dropper or similar mechanism of dispensing one drop at a time Vernier caliper for measuring outer diameter of pipette’s exit(?) Glass slide (biology-type) Teflon tape or Water Proofing Spray High speed camera (or video)

7. How could the experiment be setup? Coat microscope slide with soot from burning candle Apply several fine coats of water-repellant to soot-covered slide Pipette positioned directly above microscope slide Water droplet is released Measure/record water droplet velocity prior to impact, contact time with hydrophobic surface, and droplet deformation