Estimating the Diameter of the Moon Using a Pencil - Simple Physics Problem

[k_yup]

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.

 

[LowlyPion]

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.

How far away was the pencil from your eye?

 

[k_yup]

about 15cm

 

[k_yup]

so use simular triangle theory?

 

[LowlyPion]

so use simular triangle theory?

Yes, that would do it nicely.

Sorry for late reply I guess I missed it last night when I scanned the board.

Good luck.