# 2.8 Problem Set

1. Calculate the terminal velocity in water at 20°C for each of the following. Assume a particle density of 2650 kg m-3, a water density of 1.00 × 103 kg m-3, and a viscosity of 1.00 × 10-3 kg m-1 s-1.
1. 100. µm diameter sand particle
2. 10.0 µm diameter silt particle
3. 1.00 µm diameter clay particle
2. Determine the USDA textural class for the following soil samples:
 Sample # Sand (%) Silt (%) Clay (%) Textural class 1 26 42 32 2 85 7 8 3 33 54 13
1. Go outside and use texture by feel to find soil from two different textural classes and report the latitude, longitude, and estimated textural class. If you are in the USA, use the SoilWeb app (iOS or Android) to determine and report the expected soil series for your location. Do not trespass. Use all appropriate safety precautions.
2. The following 5.0 cm diameter soil samples that are 5.1 cm in length were dried at 105°C for 24 hours. Calculate the bulk density and porosity of each sample.
 Sample # Dry Mass (g) Bulk Density (g cm-3) Porosity (cm3 cm-3) 1 168 2 105 3 132