Equations - Only Difficult Ones

Question 1

s, not involving acceleration (involving time)

Answer 1

ᐃs = ((v + u)t)/2

Change in displacement is equal to time taken multiplied by the sum of initial and final velocities, all divided by two.

Question 2

Kinetic energy in terms of momentum

Answer 2

KE = p^2/2m

Kinetic energy is equal to the square of the momentum divided by two times the mass.

Question 3

Force in terms of momentum

Answer 3

Change in momentum/change in time

AKA

Impulse/change in time

Question 4

Impulse

Answer 4

Change in momentum

Question 5

Net force in circular motion

Answer 5

mv²/R

mass times velocity squared, all divided by radius

Question 6

Force due to static friction

Answer 6

F ≤ (coefficient of static friction)*R

Force of static friction is less than or equal to the coefficient of static friction multiplied by the normal force (acting on the object)

Question 7

Force due to dynamic friction

Answer 7

F = (coefficient of dynamic friction)*R

Force of dynamic friction is equal to the coefficient of dynamic friction multiplied by the normal force (acting on the object)

Question 8

Critical speed (circular motion - when something going over a bump lifts off)

Answer 8

v = √(Rg)

if v > critical speed, object lifts off

Question 9

linear velocity from period (circular motion)

Answer 9

v = (2πR)/Δt

because v = distance/time
and distance = circumference of circle
circumference = πd = 2πr

Question 10

intensity of light related to amplitude (waves)

Answer 10

I = k*A^2

intensity is directly proportional to the square of the amplitude

Question 11

Snell’s Law

Answer 11

n1/n2 = sinθ2/sinθ1 = v2/v1

2s and 1s here are Not coefficients! just used to distinguish the media! medium 1 and medium 2

basically the ratios of sinθ (sine of the angle of incidence/refraction) and of velocity in both media are equal and then the ratio of the refractive indices are like. indirectly proportional to both?? refractive indices are weirdos who swapped the numerator and denominator

Question 12

intensity of light incident on polariser (Malus’s law)

Answer 12

I = I(incident)*cos^2(θ)

Question 13

Fringe separation (double slit diffraction)

Answer 13

s = λD/d

D = distance from slits to screen
d = distance between slits