Datasheet

Chapter 1: Mechanical Adjustments · Page 35
Don't worry if you don't happen to have a gram scale or pulley and attachment. Thanks
to the popularity of calorie counting, dietary scales can be purchased at most food
markets and drug stores for under $10 (US). Pulleys and mounting hardware are also
easy to get from hardware stores for $5 or less, just ask where to find the sliding door
replacement parts. Figure 1-13 shows examples of both pieces of equipment.
Figure 1-13
Example of
Inexpensive Scale
and Pulley
Make sure the pulley turns freely! The calculations assume the pulley and string have no
effect on the system. In reality, they always do, so it's important to reduce their effects until
they become "negligible" compared to the other forces involved. The string should be light,
and the pulley and string together should offer next to no resistance. You may need to
experiment with different pulleys. Be creative, and don't limit yourself to door replacement
hardware. For example, you can build a home-made pulley with heavy coat hanger wire
and an empty thread spool.
Friction Force Calculations and Tests
Figure 1-14 shows the setup you will use to test frictional forces.
√ Weigh the SumoBot.
√ Build the system shown in Figure 1-14.