The answer is tighten and contract.
In order for the students to pull the rope their muscles will need to tighten and contract so they are able to continuously pull with all their strength and power. Relaxed or twitched muscles will result in release of the rope.
A cracked pan is a safety hazard because:
1. It can cause food to slip through cracks
2. It can cause injury if sharp ends come in contact with human skin.
3. Could suddenly snap due to the heat and cause various injuries
