Conceptual Physics

ș = angular size (in radians)

h = height of object

d = distance to object

What is the angular size of this

person’s thumb at the given

distance?

șThumb§ 0.05 m /0.5 m

șThumb§ 0.1 rad

How far is this person from the

Space Needle? She measures

the angular size of her thumb

and of the Needle as 0.11

radians.

șNeedle§hNeedle/dNeedle

dNeedle§hNeedle/șNeedle

dNeedle§ 184 m/0.11

dNeedle§ 1700 m