Dean of Faculty Patrick Reynolds visited Professor Gordon Jones’ “Physics 190: The Mechanical Universe” class last week to help illustrate some laws of physics. Lying on a bed of nails, Reynolds demonstrated the difference between force and pressure. In comparing a bed with a single nail to one with hundreds of nails in both cases the force (Reynolds’ weight) is the same, but the pressure is different. On a bed of hundreds of nails the force is spread over many nails in the same way that pressure depends on the area over which a force is spread.
Jones also placed a board on Reynolds, put a cinder block on the board, then smashed the block with a hammer. “Smashing the cinder block shows two things. First, it demonstrates force vs. pressure again. The small head of the hammer on the brick leads to a large pressure on the brick, but the board has a large area so that leads to a small pressure on Pat,” Jones explained. “Second, there is a physics concept called 'impulse' which is related to how force is spread out in time. The brick is rigid so the hammer must stop in a very short amount of time leading to a large force,” he said.
Jones reported that “Pat is more flexible (a good thing for an administrator), so the hammer has longer to stop leading to a smaller force.” Reynolds had a slightly different take: “I think he was demonstrating the difference between pliability and brittleness --- whether in materials or simply administrators, I'm not sure. I was demonstrating my absolute trust in the Hamilton faculty!”