Determining Acceleration Due to Gravity

Determining Acceleration Due to Gravity The Determination of the acceleration due to gravity at the surface of

the earth, g, using a simple pendulum.

Aim: The determination of the acceleration due to gravity at the

surface of the earth, g, using a simple pendulum

Background

==========

All bodies exert gravitational forces on one another. A large mass,

such as the earth produces a gravitational field.

Gravity acts between any two objects, causing a force of attraction

which tries to pull the two objects together. An example is if you

release an object above the ground it falls down as it is pulled down

by gravity.

My investigation aims to allocate a value to the acceleration this

object would experience due to the earth's gravity.

Isaac Newton first discovered gravity when an apple fell on his head.

He discovered that every object has a mass and that two masses attract

each other. Newton wanted to calculate the gravitational field

strength of the earth i.e. what size the acceleration objects, such as

the apple experienced, due to the earth's gravity.

I am going to determine this value, not using a free-fall object, but

a simple pendulum. A simple pendulum consists of a mass, suspended

from a fixed point by a length of string. The forces acting on the bob

(mass) of the pendulum are tension in the string (t) and weight (mg)

as shown.

When the bob is displaced from its equilibrium position, with the

thread taut and then released it oscillates about the equilibrium

position in a fixed vertical p...

... middle of paper ...

... eliminate reaction time of the experimenter having effect on the

results. Perhaps a laser beam could be used as a sensor to count the

oscillations. If connected to a logger, the number of times the laser

beam is interrupted, by oscillating pendulum count be used to

determine how many oscillations have been made. The calculated period

would be more accurate and precise if error such as the above could be

eliminated and the experiment bettered and the margin of uncertainty

made much smaller.

The value I have found is a value for the acceleration due to gravity

at the earth's surface only. The earth's gravitational field varies

all over the earth. It would be interesting to see how much it varies

and by how much. For example, it is said that at the equator the

acceleration due to gravity is different to at the poles.