Solid Rock to Building Block
This modern equipment, a bulldozer, acts as a wedge to move soil and rocks in a quarry.Copyright National Park Service, U.S. Department of Interior, http://www2.nature.nps.gov/geology/aml/.
Students continue their pyramid building journey, acting as engineers to determine the appropriate wedge tool to best extract rock from a quarry and cut into pyramid blocks. Using sample materials (wax, soap, clay, foam) representing rock types that might be found in a quarry, they test a variety of wedges made from different materials and with different degrees of sharpness to determine which is most effective at cutting each type of material.
An important job for any engineer is to assign appropriate tools for building, machining and manufacturing. A wrong choice may result in a poor quality final product and/or a tool that wears out or breaks quickly. For example, a dull wooden wedge used to cut solid rock is only successful for a short time before it breaks or wears down to the point at which it no longer cuts. Engineers calculate the amount of force required to cut through a given material; knowing this helps them choose the most appropriate tool material that will cut through the rock material.
After this activity, students should be able to:
- Determine how different materials break using differently-angled wedges.
- Describe why simple machines are used and how a wedge exerts a force.
- Demonstrate why material selection and material science is important to engineers.
- Understand that because simple machines do their jobs so well they are still used today.