# Recent content by ghostbuster25

1. ### Resistivity - Need definition

I am revising for my A levels and I have noticed that a common question on the paper is to define RESISTIVITY. I have looked and looked but found no definitive description or a good definition. I know the formula but is it right to just say that "resistivity is directly proportional to a...
2. ### Force in circular motion

Just wondering if anyone can check over my answer for a question. Q) A 1.7kg object is swung on the end of a 0.6m string in a vertical circle. The object does one revolution every 1.1s. What is the tension in the string at the top of the circle? and the bottom? A) m=1.79kg r=0.6m...
3. ### Geometric progression

just a check of my work please. I have to write an expression for the nth term of this geometric sequence. a1=100 a2=106 a3=112.36 I've worked out the ratio to be r=1.06 I am using the formula un=ar(n-1) so the expression i have come up with is un=100(1.06)(n-1) Is this correct? I have...
4. ### Series and sequence

sorry i made a mistake in the question part, it is supposed to read u1=-1
5. ### Series and sequence

Just a check of my work please, The topic is series and sequence, Question: The sequence u1, u2, u3,..... where u1 is defined by u1=2 and Un+1 =un+4 Find the nth term, un, of the sequence. I got the answer, u1=-1 u2=-1+4= 3 u3= 3+4 = 7 So: un = 4(n-1)-1 This seems to work but not sure if...
6. ### Calculate the Current, Lost Volt and P.d across parallel resistors?

I'm pretty sure the lost volt is the resistance inside the battery. Once you work out the lost volt you can minus that from the voltage of the battery and work out the real value of V. Most questions dont include thw lost volt because it is quite small and considered negible. I think they are...
7. ### Displacemnet along a spring

hi thanks that kinda makes sense, im just having trouble with the amplitude...x0...how do i work this out and fit it in?
8. ### Amplitude of a wave

Hi, does anyone know how to calculate the amplitude of a wave knowing the frequency and wavelength
9. ### Displacemnet along a spring

i got 0.2m for the wavelength but am not sure how to use this in the equation would it be -0.2cos5t ?
10. ### Displacemnet along a spring

Hi guys, Having trouble with a question I need to know the displacment of a point on a spring at certain times. At t=0 point p is at its maximum displacement at 2cm point A is further down the spring at p-A = 0.4m A transverse wave of frequency 5Hz is moving along the spring at...
11. ### Simultaneous polynominals

i thought i was just to put the factor into the equation. Not sure what other way to do. Is the second part correct?
12. ### Simultaneous polynominals

simultaneous polynominals!! stuck on this coursework question The cubic polynominal f(x)= 4x^3+ax^2+bx+6 has a factor (x-2) when it is divided by (x+1) it has a remainder 0f -15 find the values of a and b I did as follows factor (x-2) f(-2) 4(-2)^3+a(-2)^2+b(-2)+6=0 equals 4a-2b=26...
13. ### Drawing graph of function

I have been asked to draw the graph of the function f(x)= (x+3)/(x-2) I have found where it cuts the y axis by putting x=0 but am unsure of how to find the x value. I found the inverse of f(x)= (x+3)/(x-2) which gave me x= (y+3)/(y-2) then set y=0 which again gave me x=-3 I have checked...
14. ### Composite functions

ahhh yer that makes sense :) thanks
15. ### Composite functions

is it because g is a gunction of x, not x itself!? am i doing it correctly then? :)