A screw has been attached to our slab, as we turn the screw the slab is lifted a certain distance. How far it is lifted each turn is determined by how far apart the threads are. The number of threads per a given distance is called thread density.

You will test our flood gate using several thread densities. The force applied and the distance the gate is lifted will be recorded. Select a thread density and click on <lift>.

Be sure to copy these numbers into your lab packet after each test. Test at least 4 different settings.

• Use the data from Table 1 to complete the graphs in your lab packet to help you interpret the data.
• As the # of threads increases what happens to the distance the wheel is turned to lift the gate?
• As the number of threads increases what happens to the amount of force needed to turn the wheel?

• Discuss the relationships shown on graphs A and B with your partner.
• In your own words explain how an increase in thread density changes the distance the wheel is turned and the amount of effort force needed to lift the slab. Be sure to use complete sentences.