Simple Sundial

For this experiment you will need a piece of string (about as long as your height), something small and heavy you can tie onto one end of the string as a weight (e.g., some washers or bolts, a small rock) and a piece of chaulk (or something to mark the ground).

(1) A Simple Sundial: Take a weighted-string and a piece of chalk. Find an open, flat place and mark the ground with an X using the chalk. Hang the string over this mark. Note the shadow. Keeping the weight as still as possible over the X, mark the ground at the point of the shadow of the knot in the string. Remember which mark is which--you will be returning later. Where do you think the shadow will be in approximately 20 minutes?

(2) 20 minutes later - return to your sundial. Hang the weighted string again over the original mark.

(a) Has the shadow moved in the direction you expected?

(b) Mark the new location of the shadow of the knot with another X. Connect the Xs. The direction of the line connecting the Xs should be close to east-west. Does your line look like it runs east-west?

(c) This shows how a simple arrangement of a string (or a stick or anything fixed that makes a shadow) can be used for navigation. Describe how a similar arrangement could be used as a (crude) measure of time?