Tension in a String

Comparing the weight of a mass hung from a single spring scale to the weight shown on a spring scale between two masses over pulleys demonstrates the principle of tension in a string. When a mass is hung from a single spring scale, the scale directly measures the gravitational force acting on the mass. In a setup with two masses over pulleys and a spring scale in between, the tension in the string remains constant throughout, showing the same reading on the scale, illustrating how tension distributes forces equally along the string regardless of the number of masses.