Sun shade on Earth ground, is it a straight line or a curved line?

[applied-physics]

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Hi, I wonder if the shade from the sun on the ground, on a sunny day, is it a straight line or a curved line?? and if it is curved, how curvature can be calculated ?? Let´s say I have a pole or building, and I can follow up the shade of its top on the ground. I can make marks every 5 minutes or so. . Would that make a straight line, or a curve line ?? Thanks !

[Hi , I am an Electrical Engineer who has been teaching High School Physics for a while here in Santiago of Chile. I started with the Cambridge-IGCSE curriculum, and then I moved to the local curriculum. My interests are waves, ultrasound, near-infrared, electrical power systems, relies, universe and comets! Following Pons Brooks (perihelium April 21st 2024, nice shot here from Southern Hemisphere!), Tsuchinshan, ... others ! ]

 

[berkeman]

Welcome to PF.

Hi, I wonder if the shade from the sun on the ground, on a sunny day, is it a straight line or a curved line?? and if it is curved, how curvature can be calculated ?? Let´s say I have a pole or building, and I can follow up the shade of its top on the ground. I can make marks every 5 minutes or so. . Would that make a straight line, or a curve line ??

What are your thoughts so far? Do you have any ideas how you could sketch the situation to try to figure this out? It likely depends on your latitude and the day of the year, right?

 

[Nugatory]

Your pole is an enormous sundial, is it not?

 

[applied-physics]

ooops, .. that is right ... that used to be a science fair project ... indeed a pole can be a sundial, right. I could make a clock. And the angle then will depend upon latitude. 33 south is mine here in Santiago. Many many thanks.