General Tips Flashcards
If they ever ask you about a ratios of any sort
put it into FRACTIONS!!!
If there is a question “ a^2 -b^2”
This is the same as saying (a-b)(a-b)
If there is a question that asks you 1.001^6 -1.001^5,
Just do : (1+0.001)^6 -(1+0.001)^5
Hence:
1 + 0.006 - (1 + 0.005)
1 + 0.006 - 1 - 0.005.
If they say “x= |2|”.
This means that there are lines on both x=-2 and x=2.
Whenever they give you any random shape,
IMMEDIATELY WRITE DOWN ALL THE DIMENSIONS! ESPECIALLY THE RADIUS/ DIAMETER!!!
When you see some values and a graph
Create an equation for the graph, often you will have to use integration etc to be able to solve it and the following questions
If they’ve given you numbers, which feel irrelevant
NO!! THEY AREN’T IRRELEVANT! They wouldn’t give you numbers if you didn’t need them, so USE THEM! Put it into a fraction, or an equation!!!
List all the data they’ve given you so you can know what to do with it.
When something is increased by 20%
use multiply it by 1.20.
Pressure equation
P= DENSITY * G * DEPTH.
Transformers equations:
Vp/ Vs = Np / Ns
Can use Current in place of V too if you want- they are proportional.
What combination of conditions gives the lowest rate of thermal energy transfer?
The lowest temperature difference. The highest length to travel, and the smallest diameter
What are the diagonals of a rhombus.
The lines that connect 2 of the furthest points together.
Whenever you see triangles
Look if you can apply the Familiar triangles method.
REALLY IMPORTANT THING THAT KEEPS OCCURRING
Usually, they will get you to create 2 equations, and then eventually use them together to get the solutions.
For momentum questions, for 2 objects hitting each other
Be careful when calculating the force- often they may only want you to find the force on only 1 object. So RTFQ!!
When you have 1/(x + y)^4
try to rationalise the denominator first, always!! Then, just multiply the (x + y)^4, by (x - y)^4. You can multiply just the brackets, and then by the indices.
Whenever you have an object at an angle, and you are told to calculate the normal force:
multiply the Weight of the object by the perpendicular centre= F * d (distance where there needs to be a normal)
If there is a rope holding the particle or something- consider the vertical force it applies as well.
Whenever you see a question about a “find the real solution” and there are indices
usually, you have replace something to be equal to y, and it’ll turn into a normal quadratic equation.
If they give you angles to the boundary, rather than the normal
you can use Snell’s law still, but just use “cos” rather than “sin”
Whenever an object is slowing down when moving upwards :
Then g is still bigger than a.
Finding the coefficient for x ^5 (a + b) ^ n
n! / 5! (n-5)!
How would you find the coefficient for x ^3 for (a + b)^7
7! / (3! x 4!)
This means:
7 x 6 x 5 x 4…) / ((3 x 2 x 1) (4 x 3 x 2 x 1)
Here, you can cancel many things.
you can often also use pV = nRT if you want to.
If they want you to use ideal gas equations, they will say :
(… assume that the temperature will remain constant as an ideal gas…) THIS IS THE CLUE OT USE PV= NRT!!!
