Which scale is used to measure weight by applying force to a spring?

• A. Balance scale
• B. Spring scale
• C. Digital scale
• D. Dial scale

Answer: (B)

Weight is a force, and a spring scale measures that force directly by how much the spring stretches under gravity. When you hang an object, gravity pulls it down, the spring extends, and the scale is calibrated so that that extension corresponds to a specific weight using F = kx. This makes the reading a direct measure of the weight. A balance scale, instead, compares the unknown weight to known masses on a lever, not via spring extension. A digital scale relies on electronic sensors to infer weight, not a mechanical spring. A dial scale could involve a spring in some designs, but the scenario described—measuring weight by applying force to a spring—best matches the spring scale.