Estimate Diameter of Moon Using Pencil Measurements

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SUMMARY

The discussion focuses on estimating the diameter of the Moon using a pencil as a measurement tool. The method involves holding a pencil at a distance from the eye to block the Moon, with the Earth-Moon distance given as 3.8 x 10^5 km. A pencil length of 1.5 cm (1.5 x 10^-5 km) is noted, and the concept of similar triangles is introduced as a crucial mathematical principle for solving the problem. Participants emphasize the importance of measuring the distance from the eye to the pencil for accurate calculations.

PREREQUISITES
  • Understanding of similar triangles in geometry
  • Basic knowledge of trigonometry
  • Ability to perform unit conversions (cm to km)
  • Familiarity with basic physics concepts related to distance and measurement
NEXT STEPS
  • Learn about the principles of similar triangles in geometry
  • Study basic trigonometric functions and their applications
  • Research methods for measuring distances in physics experiments
  • Explore unit conversion techniques for different measurement systems
USEFUL FOR

This discussion is beneficial for physics students, educators, and anyone interested in practical applications of geometry and measurement in astronomy.

k_yup
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im new to the physics world and know this is probably an easy problem but i don't know where to start

Hold a pencil in front of your eye at a position where its end just blocks out the moon. Make approprite measurements to estimate the diameter of the moon, given that the earth-moon distance is 3.8x10^5km.

i figured that you prob had to measure the end of a pencil which i measured about 1.5 cm which is 1.5x10^-5km but i don't really know what to do from there.
 
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Your also need to also estimate the distance from your eye to the pencil.
Draw a picture...there are two similar triangles involved
 

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