Table Lux
Table Lux
HELP ABOUT INVERSE VARIATION!!?
THIS IS ABOUT INVERSE VARIATION:
The intensity of light (in lux) varies inversely with the square of the distance from the source. A bulb hangs 3 meters on the ceiling, and the intensity of light on the floor is 100 lux. If the intensity of light is 225 on top of a table inside the same room, how tall is the table?
tnx in advance!!really need the help..
Let the floor be d metres below the light source, and let the height of the table be t, so that the table-top is (d – t) metres below the light.
Light intensity, I = k/d²
On the floor, 100 = k/d² , so k = 100d²
On the table-top, 225 = k/(d – t)² = 100d² / (d – t)²
9 = 4d² / (d – t)²
9(d² – 2dt + t² ) = 4d²
5d² – 18dt + 9t² = 0
We want to solve for t, so first I will turn the equation around :
9t² – 18dt + 5d² = 0
t² – 2dt + (5/9)d² = 0
t = [2d ±√ (4d² - (20/9)d²)] / 2
. = [2d ±√ (36 - 20)d² / 9)] / 2
. = [2d ±√ (16/9)d²] / 2
. = [2d ± (4/3)d] / 2
. = d ± (2/3)d
. = ⅓ d or 1⅔ d
That is, the height of the table is ⅓d, which means that the table-top is ⅔ of the distance from the light to the floor.
(1⅔ d would represent the “mirror image” of the table on the other side of the light, that is, above the ceiling, where the light intensity would, at least theoretically, be the same as this distance below it.)
Table Lux
so he finally noticed me so….???
The guy i liked at uni finally noticed me.When he came into class he looked at me first when i went out for a bit and came back in he looked at me again and while presenting he luked at me a few times and even when i was presenting he looked at me. Then when i was leaving i held the door open for him and he usually doesnt bother talking to people but he thanked and he always lux me straight in my eyes!The tables have turned because i would always look at him and he would never look and today he kept noticing me and whenever he would look i would feel like i was caught off guard so i would look away. I know i should try to keep eye contact next time but what should i do to keep him looking at me and eventually liking me? What do i say or do the next time i see him?
Smile and say “Hi” and be sure to be nice and say something like “What did you do last weekend?” Then be quiet and listen. He likes you. And don’t tell any of your friends about him…..one will go tell him you like him, too. And then it will be over, he will be embarrassed.
Joel McCrea and Claudette Colbert “Hands Across The Table” (1937) Lux Radio Theatre (1)