New Stuff Flashcards
Coefficient of friction?
Or friction equation
How to know what direction friction acting in?
Where is reaction force?
Friction = mew x R, where mew is the coefficient of friction and R is the reaction force acting on that object!
Friction in general ALWAYS OPPOSES MOTION so this is the direction
Reaction force generally from the weight resultant!
Relative velocity
RV = Veleocity of B with respect to velocity of focal point A
So RV = Vb-Va
And here you can often say the focal point is earth which is technically STATIONARY
Use equation and rearrange
For thing undergoing fission , how do you do the question
Mass gotta be conserved, just add up the protons neutrons
Can eliminate pretty quickly by just adding final digits, check first, if yes then move on to full calc if no can jus eliminate by doing so easy a sum
Losing thermal energy by convection?
If a ball of higher temp is put into room of lower temp temp will go from ball to room as it’s cooler
What about which surfaces dull or shiny emit thermal radiation more
Dull, black bodies begger
Finally how ti see which ball simply EMITS THERMAL RADIATION AT THE GREATEST RATE IN GENERAL
in general the greatest temperature and black will emit the greatest radiation
Now this question didn’t say rate, so temperatures don’t matter- as it’s in general
As it same temp as room yh it will absorb the highest too so net rate is lowest, but they didn’t ask they just set emit in general
- so look for greatest temp and blackest surface
What does coefficients of friction yield
The MAXIMUM value for friction, this is at the point where theta is increase so it’s about to slip.
Below this point use that forces equal to each other as it hasn’t hit max friction yet
How to integrate an inverse or normal function with limits
Plug in the limits into the reverse function and subtract
With volume in colour so what is constant and thus how can you find velocities and thus resultant force
The volume stays constant as incompressible
Thus as A1L1 = A2L2
As length is proportional to velocity
A1V1=a2V2
So V2 is a1v1/a2
Now you have change in velocity
Need change in momentum and the time
Make a volume up, it’s calm as it’s constant
So say 1
This gives you thr mass as 800
Now you need time
You have the length as you do volume / cross sectional area
You have velocity
So you have time
How do change in momentum over time
And you have resultant force
Simple percentage increase if it’s 100% more then what is it
X2 as total is 200% of original value
Esssenrially ALWAYS ADD OR SUBTRACT FRIM 100
There is a force at right angles to the current and magnetic field, how to find this direction?
Use Fleming left hand rule
This is where index is DIRECTION IF MAGENTIC FIELD
Thumb is direction if force
Middle is direction if current
And what is the equaruon for the force acting on a WIRE to carriers current and is in a magnetic field
F=BIL
where B is magentic flux density
And l is length if wire (or length cutting part of the new circuit
When is a graphs gradient at max or min?
This is basically the maximum or min point of gradient function
Thus differentiate again to find these points and PLUG BACK INTO FIRST DERRIVATIVE
Relative velocity perpendicular
The relative velocity forms the hypotenuse
And the thing it’s relative too goes in the other plane
In maths if you have two numbers multiplying to the power of something what can you do
Take the power out or distribute the power!
