Cheatography

# Physics MidTerm 2 Cheat Sheet by brandenz1229

Goes over...Chapter 6: Work and Kinetic Energy Chapter 7: Potential Energy, Energy Conservation Chapter 8: Momentum, Impulse, Collision

### Chapter 6: Work and Kinetic Energy

 m = mass g = 9.8 m/s F = Weight (N) F = m ⋅ g s = distance K`E` = Kinetic Energy W = Workdone Power = P (Watts) x = cos y = sin 1 km = 1000m 1kg = 1000g ΔK = K`f` - K`i` Friction = always negative g = -9.8 (decre­asing) g = 9.8 (normal) a = g (gravi­tat­ional accele­ration) Θ = Angle between F and s || = Component of F parallel to dl v = velocity W = (∫P`2` to P`1`) F⋅dl W = F`||` dl W = (∫P`2` to P`1`) F⋅cosΘ⋅dl W = F ⋅ s (Joules) P`av` = ΔW / Δt P = lim Δt > 0 (ΔW / Δt) = dW / dt V`f` = V`i`2 + 2 ⋅ a ⋅ s P = (W/t) Constant Speed : (a = 0) F = force P = F ⋅ v Friction (opposite) = cos(180o) W`x` = F (cosΘ)⋅s || W`y` = F (sinΘ)⋅s a = (V`f`2 - V`i`2) / (2⋅ s) F`s` = (1/2)⋅m⋅V`f`2 - (1/2)⋅m⋅V`i`2 W`grav` = m⋅g⋅h P = (W/t) K`E` = (1/2)⋅m⋅V2 P`E` = m⋅g⋅h

### Chapter 7: Potential Energy, Energy Conser­vation

 Potential Energy = U, P`E` ΔK = -ΔU`grav` K = Kinetic Energy R = Radius s = y`f` - y`i` U`grav` = m ⋅ g ⋅ y Δs = Δxî + Δyĵ `cm` = circular motion k = constant of spring P`E` = (1/2)⋅k⋅x2 W`grav` = w-vector ⋅ Δs-vector Diameter = 2 ⋅ Radius W`f` = Work Done by Friction if elastic... K`E` = P`E` W`grav` = F × s W`grav` = m ⋅ g ⋅ y`i` - m ⋅ g ⋅ y`f` K`i` + U`i` = K`f` + U`f` (1/2)⋅m⋅V`i`2 + m⋅g⋅y`i` = (1/2)⋅m⋅V`f`2 + m⋅g⋅y`f` if gravity does work.... E = K + U`grav` W`total` = K`f` - K `i` W`total` = W`grav` + W`el` + W`other` W`other` + U`i` - U`f` = K`f` - K`i` arrange to.... K`i` + U`i` + W`other` = K`f` + U`f` Work done on a spring W = (1/2)K`E`⋅X`f`2 - (1/2)K`E`⋅X`i`2 Work done by a spring W = (1/2)K`E`⋅X`i`2 - (1/2)K`E`⋅X`f`2 U`cm` = m ⋅ g ⋅ R Elastic Potential Energy U`el` = (1/2)⋅K`E`⋅x2 Work Done by Elastic Force W`el` = (1/2)⋅K`E`⋅x`i`2 - (1/2)⋅K`E`⋅x`f`2 if elastic force does work, and mechanical energy is conserved K`i` + U`el`, `i` = K`f` + U`el`, `f` Work Done by Friction: W`f` = -W`fric` W`f` = -(-f`k`⋅ s) W`f` = μ`k`⋅m⋅g⋅s Law of Conser­vation of Energy ΔK + ΔU + ΔU`int` = 0 F = F`x` + F`y` + F`z` F`x`(x) = -m⋅g F`y`(y) = -m⋅g F`z`(z) = -m⋅g F`x` = (1/2)⋅K⋅x2

### Chapter 8: Momentum, Impulse, Collisions

 p = momentum J = Impulse m = mass v = velocity P = m ⋅ v (kg ⋅ m/s) F = d`p` / d`t` J`y` = (∫t`f` to t`i`) ΣFy dt J`y`= (F`av`)`y` (t`f` - t`i`) J`y` = P`fy` - P`iy` J`y` = (m⋅V`fy`) - (m⋅V`iy`) J = ΣF (t`f` - t`i`) J = ΣF⋅Δt J = (∫t`f` to t`i`) ΣF dt J`x` = (∫t`f` to t`i`) ΣFx dt J`x`= (F`av`)`x` (t`f` - t`i`) J`x` = P`fx` - P`ix` J`x` = (m⋅V`fx`) - (m⋅V`ix`) ΣF = (P`f` - P`i`) / (t`f` - t`i`) J = F`av`(t`f`- t`i`) J = (P`f` - P`i`) = {F} : Change in Momentum P = P`A` + P`B` = |P`A` + P`B`| Assuming m`1` and m`2` don't change m`1`⋅v`1`+m`2`⋅v`2` = constant (P`1`+P`2`)`i` = (P`1`+P`2`)`f` P`1`+P`2` = constant P`i` = P`f` V`f` = (m`1`⋅v`1`+m`2`⋅v`2`) / (m`1`++m`2`)