1J30.35 Rope and Two Students

A long rope is suspended between a fixed object and a strong student. Pulling along the rope, a weaker student will find it difficult to displace the stronger student. Pulling perpendicular to the rope, the weaker student easily wins the tug of war. Alternatively, this demo can be done by having two stronger students pull on the ends of the rope, instead of one stronger student pulling on one end with the other end attached to the wall. Then it looks like a single student single-handedly overpowers two others by the sheer power of physics.

For small angles, 1/sin(θ) is large and for a small force F the tension required of the stronger student to resist being dragged is large. For example, at θ = 10˚, 1/sin(θ) = 5.8 and T ≈ 3F to be stable. The student pulling at the end of the rope would have to be three times as strong as the other student to avoid getting pulled when θ = 10˚.

 

Locations: Manila Rope D2-6