# Recent content by DB

1. ### Very easy question

simple question, if the derivative of cos(x) as x->0 is 1, the is the derivative of cos(3x) as x->0 = 1 aswell?
2. ### Having a little trouble, very typical question

thanks everyone, btw hallsofivy displacement is a vector, distance is not. just to cleat that up :) thanks again i understand the problem now
3. ### Having a little trouble, very typical question

oh im sorry, it is suposed to say 100m North
4. ### Having a little trouble, very typical question

sry, i cant find the mistake your talking about, would that 85 be -115?
5. ### Having a little trouble, very typical question

im not use to working is 3D so i need some help you are going to a restaurant. you leave your apartement and take the elevator 30 m down, then 15 m south to the exit. then u travel 200 m east and then 100 m to the restaurant. what is your displacement. so what i did is: -30k -15j...
6. ### Simple question, tangent line

finally, got it
7. ### Simple question, tangent line

thanks for the replies, but i dont understand how the c.d is 2h(2+h)
8. ### Simple question, tangent line

but those are different terms, arent i looking for a common denominator?
9. ### Simple question, tangent line

i dont understand
10. ### Simple question, tangent line

thanks okay stupid mistake, now im stuck again tho \frac{2}{2(2+h)}-\frac{(2+h)}{2(2+h)}*\frac{1}{h} comes out to \frac{-1}{h}}*\frac{1}{h} gives me -1/h which doesnt work, darn
11. ### Simple question, tangent line

really isnt calculus but thats the name of my class so, anyway im having a problem here. i think its pretty simple im just missing something. im supposed to find the slope of the tangent line using one point and: slope of tangent line = \frac{f(a+h)-f(a)}{h} h\rightarrow0 find slope...
12. ### Circular motion question

nvrm, the it is F \propto f^2mr thanks tho
13. ### Circular motion question

doing a lab report on circular motion and was asked to make a combined proportionality statement, just asking yes or no, is this right? F_c \propto f^{2} \propto a_c \propto \frac{1}{m} \propto r where "F_c" is the centripetal force, "f" is frequency in Hz, "a_c" is the centripetal...
14. ### How do they know the universe is expanding

are you saying that space is infinite?
15. ### How do they know the universe is expanding

I see, so really the notion that the universe is still expanding today is an assumtion?