Tie a piece of string around the sunflower seed. Tie in a manner so the string does not rest on the flat surface, as this interferes with the final measurement.
Tie the end of the string to the hooked end of a spring balance.
Level the spring balance with a table. This ensures you pull on the seed with as much horizontal force as possible. Pulling while the balance sits above or below the flat surface interferes with the balance's measurement.
Gently pull on the spring balance while continually adding more force until the seed begins to move. Locate the dynamic friction measurements on the side of the sliding balance and record the measurement. The spring balance elongates as you add more force. This occurs when the top half begins to pull out of the bottom half. The measurement tool on the side records the displacement that occurs. Record your findings. This gives you the sunflower seed's dynamic friction.