Centroids: The Last Part

Using MDSolids I found the centroid of beam cross sections for two Flanged shapes. After making dimensions it computes where the centroid would be.

Activity 2.1.5 Calculating Moments

Conner Lewis did a great job holding the meter stick

Activity 2.1.4 Calculating Force Vectors

Manila Folder Bridge Part I

Quinn, Conner and I worked as a team today for this design build challenge.

Criteria: Build a structure that can support as much weight as possible over a 18" gap.

**Magazines will be the weights and two separated tables will be the gap**

Constraints Part I:

Materials:

• 2 Manila Folders (letter size)
• 2 feet of tape (may not use a piece of tape longer than 6")

Weighing: 

• Magazines will be used as "weights"
• Your "score" for our competition is determined by how many magazines your structure supports!
• Magazines will be added to your structure one at a time until "failure" is achieved
• You may place magazines anywhere on your structure as long as:
• All magazines must rest between the two vertical edges of the gap your bridge is spanning (magazines must be over the "gap")
• No magazines may tough the tables (magazines may not be piled up to "self support themselves)

Construction Practices

• Only one end of your design may have a "pinned" connection to the table top (i.e taped). The other end must act as if it were on a "roller" connection (i.e. laying on the table top).
• Manila folders may not be layered more than 3 layers thick at any location.
• Parallel structural members may not touch directly (they can be connected via non parallel connection members (ex. a "ladder" style design))

Our Design:

• Plan 1: fold the manila folders into thirds and place them across the gap connecting them with a few folded strips in the center
• Plan 2: make a design like the bed of nails on Mythbusters- make a lot of little pyramids out of one folder and then tape them all over the other one that is spanned across the gap to try and distribute the weight of the magazines
• Plan 3: use the manila folders and fold them into thirds and create a triangular prism place them side by side separated by two inches across the gap
• Final plan: make the folders into triangular prisms and put one inside the other across the gap

We managed to somehow get 50 magazines on our structure for a brief second before we achieved failure!

Centroids Part II

We finished part II of the centroids packet today with our table groups. Corin, Conner, Conner, Quinn, and Mark were in my group.

The first part was to make a complex shape out of a manila folder or some foam board

Sadly part of our shape was cut out of the picture

Then using a thumb tack, sheet of foam board and plumb bob made out of string and a roll of tap

The process of drawing lines where the string hung in front of our shape

We finished drawing lines from all of the corners using the plumb bob

This is the first side we tried

Turned out our approximated centroid location was off so we tried again

We redid the lines on the other side

This time we made a little bigger holes to allow more free movement

Our new approximated location for the centroid was much more accurate

Using a finger on the centroid we could balance the foam board shape

Yay!!!

Beam Deflection

My team members were Corin, Conner, Conner, Quinn, and Mark. Using a 2x4, a few phone books and magazines, and a measuring tape we would use beam deflection to try to calculate the weight of a group member.


Mark was our first attempt

Conner L. was our second attempt

It was pretty cool to see how close we could get to the actual weight of the person.

Centroids Packet

Free Body Diagrams

Fish Bowl and Logs in Container

Stop Light and Questions