Answers Flashcards
A potential dicider circuit , can one resistance be proprtional?
No meber completely proportional becsuse if value of other resitsnce
Explain why resitsnceis constant, say
The gradient is fairly linear to thst point and show a clacualtion
Gotta see the parallel circuit, don’t assume no resistance
How to get greatest swing on potentiometer
If your resistor so low, no matter what happens to variable resistor (goes low) goes high, then it doesn’t matter itwon’t make too much of a difference lol
If it is so high, then again it will just take majority volt anyways so not much difference
Therefiremudt be as close to middle of the range thst variabel csn go to, do that the effect actually seen
So if your range 100-1000 and reguakrly moves through this, you want it to be at 550 ideally
How to make a potentiometer
What does this let you do
And why do you use a bother permanent rejector if it’s something like a light bulb
Basically arrow is half way through permanent resistor, connect you comoientnand ammeter in series and then voltmeter in parallel
This lets you measure the full range of volstage fromm0 to abwäge
Nothing is there to limit the current of the bulb, thus use a resistor that lowers current to protect it
Why might yiu need to add a resistor!
To protect component reducing resistance, check the specs they giv you
Okay what is not equal to emf when there is internal resistance
How is internal resistance alwyas plot, don’t complicate things
Itsalways jus split like potential divider to resitsmces in the whole circuit
The electrical energy produced is the terminal pd
The chemical energy thst is converted is = to the emf, but then this is lost aswell
So electrical energy produced is not emf
When talking about something being less bright what can you talk about
Talk about what happened ti voltsge and curren t(because resistsnce increased) and thus power
So basically don’t just say voltsge decreased if you can
Explain why when a s write is closed voltsge is lost
This is because
- batterynhas internal resistance, so this causes lost volts as the charge carriers lose energy as heat when being cinverted . This is because the emf is now split between the internal resistance and the external resistances tin
Thus voltmeter drops
How to do gravity into frictional lost
So work out how much FIRCE yiu should’ve had at the bottom by converting work done into gpe
Then do f= ma which tells you how much you acc have at the bottom
Subtract
This is frictional work
I guess when doing height vs,cusktions try use the best variables possible so not over complicate
So like take values thst are actually relevant to the path etc
HOW TI FIND ANGLE BETWEEN KICK SND PROJECTILE MOTION
NEVER USE DISTANCE! USE YOU INITSL VELOCITY HORXINALT AND VERTICAL AND DO TAMN
Safe answer when do projetileshave highest kinetic energy
If not air resistance,e then either at the start or at the end because thatsgreatest velocity
But because if resistance, start is always corrects reistsnce can cause less velocity at the end thus
Energy change from GPE TO KE
GOE ti KE which chnaged to heat energy
Even when applied by air resistance this creates heat
MAKE SURE WHEN DOING MOMENTUM THINGD OR ANYTHING TI CHEKC GHR DIFECTIONS , CAN GET WHOLE ANSWER WRONG!
Why does material of object something is landing on importsnt to calculate Montur and forces etc
Because a softer material means time of impact is longer so force of impact is LESS
If harder then time is less, force is GREATER (and so more likely to break)
However apparently a softer Landing decreases change of momentum so it reduces height? Idek waffle
Remmeber why does a car force decreases
Beachside is speed increases drag increases by square, meanin resultant force decreasing and decreasing
Once the thrust = resisitve firces (air and friction) then it will move at terminak velocity
Remember for anything Archimedes type principle don’t find shortcuts just state the principle and work from there
Also remmeber uothrust isn’t mg its d h g a
Why is densities the main factor to see if something flowt or sink
Because volume is constant in bith, so that cancels, it ends up going down to doenskth over density
Why model wood as diver
Similar density sd human
Which is required as humans dive than float agsin
Describe and explain how resuktentnfirfe on wooden cylinder wires from moment it is fully submerged
Basically above the ground it has resultant five G, which decreases as it gains speed and thus drag. So it is decreasing acceleration
Upon entering the water the reduktent firfe decreases and once fully submerged,Erreger the resuktsnt firfe is upwards made from uothrust which is always more than the weight and drag.
However as it begins to decelerate and lose speed it loses drag too, so resultant FIRCE upwards decreased until at loses tpoijtnthere is no drag , just resultant force upwards caused by the drag
This results in the bidy ti begin to accelerate upwards, gaining resultant force as drag acts once again as it gains speed and gains drag too, until it eventually hits the surface where it floats and uothrust is now = to its weight snd now constant velocity .
Bruv check equilibrium questions that atleast net force is 0 first, makes ir a lot lot easier!
Don’t be dumb , remember for equilibrium , it has to have net force 0 in every plane, and also net moment 0 about any point . Thus if you stuck with firces, or stuck with moments LOOK AT THE OTHER ONE FOR HELPPP
Make sure to use all formulae first
Why when a car lowers on fuel does it become faster overall
Decrease in fuel means increase in acceleration, so maximum acceleration and deceleration increase
The MAX SPEED IS NIT INCREASED BECAUSE MAX THRUST IS STILL THERE, limited by drag
What is centre of mass
Point at which all the mass is said to be cicnentrated at
Point at which if a FIRCE is applied through the centre of mass, no rotational movement is seen
FOR SIGNRICANR FAIGURE WHAT TO DO
Make sure you do lowest in the answer and if it is 0 then make sure you WRITE THIS LOSE A MARK
Moments remember why do we often not twke the horizontal component of tension
Be Ayse it runs in the samemplame as the pivot
Remember for PREFIX CONVERDIONS, JUST ASSUMED GIGA IS 106 WHEN IRS TO THE POEER OF 9 FIX UP
Make sure when explaining explain all thoughts, give directions and moment key terminology for Marks
In seiosmeter question why does the one go up and not down straight away?
Downarads accekerwtiin if the ball is mucus keds than the frame so relatively frame goes down whilst ball stays where it is and then a mark goes up, however then it goes downnagterndue ti spring and it moving too
Don’t be fooled! If something is IDENTICAL MATERIAL , but less area and length (which you know to not contribute ) wha this young modulus
Still the same! Same material = same young modulus
BRUH how to work out energy stired elasticallg in young modulus equation
Basically itnis the same as 1/2 f x X
So make equation fir force and sub in 😭 acc sad
BRUH ir said OJE SLRING , don’t get caught out by two springs when it already became one be careful
Confirmed = thermal energy in loading unloading is just ?
Area in between
Bruv you were correct for spring constant strain energy forumsl is still 1/2 k x 2 or 2/2 f x just need to sub in k is stiffness and if not then sub in for,usk for f that’s calm
Springs or cables, if in series the force across both is the SAME, don’t confuse and add force from cable
!!
Remember low resitivty means high current, so it made sense for it to go around the ring and middle for mechanical strength !
Make sure proprtionsl laws etc are still good!
Abkut waves and snell
Remember equation fir n , is ratio of speed of something in thr speed of light
When something gets refracted snd becomes faster, wavelentgh becomes lomger, and wavelentgh becomes shorter if it gets slower
The lower the reflarsfive jndex if entering the greater the angle
And also if they refract by same amount probably because they have the same refractive indes
Coherence primarily conserves what! Frequency or phase difference
It conserved PHASE DIFFERENCE , and as a result sre the same feewuency !
