25 Feb, 2013
Of a spring
PRESENTATION: The force of an elastic system such as a spring can be estimated when a mass connected to it is moved from its position of equilibrium. The frequency of the oscillator can also be calculated. Different set-ups can be tested (in series or in parallel) of springs and masses. Introducing the oscillator into water or oil can also be used to analyse its behaviour when damped.
- A Simple Experiment for Determining the Elastic Constant of a Fine Wire, W. Larry Freeman and Ronald F. Freda, Phys. Teach. 45, 224 (2007)
- A Spring, Hooke’s Law, and Archimedes’ Principle, Irina Struganova, Phys. Teach. 43, 516 (2005)
INTRODUCTION: The English scientist Robert Hooke was outstanding for his studies in Physics and Biology and, in 1660, he formulated what is now called Hooke’s Law.
OBJECTIVE: To study the recovery of a spring by allowing several masses to oscillate and measuring their period.
MATERIALS: vertical stand with base, spring, set of weights, chronometer, electronic scales.
SETUP: The base and the bar give us a support from which to hang the spring down in a vertical position. Different masses made of small plastic bags of flour are suspended from the bottom of the spring. When the mass is suspended, the spring stretches to reach its position of equilibrium. If a force is applied, it begins to oscillate, which allows us to know its period.
EXPLANATION: When a mass, m, is suspended from the vertical spring, the spring stretches under the action of the weight of the mass until it reaches a point of equilibrium. By applying an additional force to make the spring longer and then releasing the weight, an elastic restoring or reaction force appears which makes the mass oscillate with a simple harmonic motion. By noting the time it takes for the system to make 10 oscillations we can calculate the corresponding period. This process is repeated for each mass. According to the equation, we can calculate the recovery constant or stiffness, k.
CONCEPTS: elasticity, M.A.S., elastic force, recovery constant, elastic spring, Hooke’s Law.
- R. A. Serway, J.S. Faughn, Fundamentos de Física, Thomson, 2006.
- J.M. Gere, B.J. Goodno, Mecánica de materiales, Cengage Learning, 2012.
- E. Burbano García, S. Burbano de Ercilla, C. García Muñoz, Física general, Tébar, 2003.
STUDENTS 2012-2013: Alberto Molares, Uxía Alonso, Enrique Alonso, Carla Carballal
LINK pdf STUDENTS (in Spanish):