Ladder as Working Platform
After watching a late night TV commercial about a folding extension
ladder, Debbie thought she could use it to help her re-shingle her roof. The
problem is she needs a flat surface to work on, but the roof has a slope of 38
degrees. However, this special folding extension ladder can pivot around the
center joint which will allow it to be positioned on the roof as shown at the
Debbie, who is a structural engineer, is concerned that the joint will
experience high loads and may fail.
What is known:
- The folding extension ladder has two legs, each are four feet long.
- Debbie, the person to work on the ladder, weighs 150 lbs.
- The roofing material will be stacked on the left side of the platform. The
material weight is assumed to be a linear distributed loading as shown.
- There is a temporary support wood strip attached to the roof that stops the
ladder from sliding. This boundary can be assumed to act like a fixed pin joint.
- The ladder pivot point is locked and will not rotate.
- The top leg rests on the roof. It is assumed that the roof is smooth (no