A Portable Timed Pendulum as a Relative Gravimeter

Abstract

A gravimeter is a device that measures the strength, g, of the Earth's gravitational field. To obtain high precision to a fraction of a milligal requires a complex and expensive instrument. However, precision of the order of 10 milligal can be achieved with an ordinary physical pendulum, which insufficient accuracy for students to measure the variations in the gravitational field in a variety of field environments. In particular, a well crafted pendulum will enable our PHSC 200 students to study the variations of the gravitational field as a function of altitude as they ascend Mauna Kea on the Big Island of Hawaii. Our pendulum acts as a relative gravimeter with a fixed length. Its simple constructions facilitates easy the transport and set-up. A simple timing device measures the period to a high precision over just a few oscillation. The construction, calibration and testing of the pendulum is described.

Discipline: Physics

Faculty Mentor: Dr. Orla Aaquist