Application of springs in instruments: in a spring balance, what is the primary function performed by the spring?

Introduction / Context:
Springs are versatile machine elements used to apply load, absorb energy, control motion, or sense force. A spring balance is a classic device where a spring’s deflection is used as a measure of an applied load.

Given Data / Assumptions:

• Linear elastic behavior of the spring within its working range.
• Deflection is proportional to applied load (Hooke’s law).
• Scale calibrated to convert deflection into force units.

Concept / Approach:
Hooke’s law states F = k * x, where k is the spring stiffness and x is the deflection. In a spring balance, the measured deflection is mapped through calibration to indicate the magnitude of the applied force or weight.

Step-by-Step Solution:

Verification / Alternative check:
Recalibration with known weights yields linear scale marks if the spring behaves linearly.

Why Other Options Are Wrong:
“To apply forces”: Springs can apply preload, but in a balance the key role is measurement.“To absorb shocks”: That is a suspension spring function, not the primary purpose here.“To store strain energy”: True physically, but the device’s purpose is to measure force via deflection.“Constant torque” applies to spiral springs in some instruments, not a generic spring balance.

Common Pitfalls:
Ignoring creep or nonlinearity; neglecting temperature effects on stiffness for precision balances.

Final Answer:

to measure forces