Physics Cheat Sheet

Physics Cheat Sheet 1

5

Units

SI: m, kg, s area: m2 , volume: m3 velocity: m/s, acceleration: m/s2 Common Conversions 1. 3600 s = 1 hour 2. 5280 f t = 1 mile 3. 1.094 yards = 1 meter 4. 1.609 km = 1 mile 5. 2.54 cm = 1in 6. 1 m/s = 2.237 mi/hr 7. 745.7 W atts = 1 hp (HorseP ower) 8. 1 mL = 1 cm3 Common Physical Constants 1. c = 2.998 × 108 m/s (Speed of Light) 2. g = 9.81 m/s2 = 32.2 f t/s2 3. gmoon = 1.62 m/s2 ≈ 61 gearth 4. G = 6.674 × 10−11 N m2 /kg 2 5. Re = 6380 km (Earth Radius) 6. Rearth−moon = 60Re (Earth-Moon Distance) 7. Rearth−sun = 150 million km (Earth-Sun) 8. ρair = 1.2041kg/m3 = 0.0012041 g/cm3 9. ρwater = 1 g/cm3

2

Density

ρ= m V Objects less Dense than Water will rise in Water. Objects less Dense than Air will rise in Air.

3

Motion: 1D

Speed must be positive, velocity can be positive or negative vav = ∆x ∆t , v = slope of x vs. t curve ∆v aav = ∆t , a= slope of v vs. t curve Constant Acceleration Processes a = constant v = v0 + at x = x0 + v0 t + 12 at2 v 2 = v02 + 2a∆x (Handy Eq.) Motion with Gravity: a = −g

4

Motion: 2D

Constant Acceleration Processes ax = 0 ay = −g vx = vx0 vy = vy0 − gt x = x0 + vx0 t y = y0 + vy0 t − 12 gt2

More Motion Formulas

v02 g sin(2θ) [Note: v2 ymax = 2g0 sin2 (θ) Tf light = 2vg0 sin(θ)

R0 =

sin(2θ) = 2sin(θ)cos(θ)]

  y(x) = tan(θ0 )x 1 − Rx0 i h q h R = R20 1 ± 1 − ymax θmax range =

6

π 4

+

gh 2v02

Newton’s Laws of Motion 1. 2. 3. 4.

7

v = constant if Fnet = 0 Fnet = ma Action = Reaction, F12 = −F21 2 F = −G mR1 m 2

Forces

Fgrav = −G MRm 2 . Near Earth Fgrav = mg. Ff ric = µN Fspring = −kx Fbuoy = ρV g Fdrag = 21 CD ρAv 2 q vT = C2mg D ρA √ m (ingrams) mi vT ( hr ) = 0.45566 D(in mm) (spherical objects)

8

Energy

units: Joules (N · m) Energy is neither created nor destroyed 1 1 mv 2 + mgh = mv02 + mgh0 |{z} 2 | {z } |2 {z } | {z } KE

PE

KE0

P E0

Types of Energy

1. Mechanical Energy 2. Thermal Energy 3. Electrical Energy 4. Magnetic Energy 5. Light Energy (Electromagnetic) 6. Sound Energy (Acoustic) 7. Chemical Energy 8. Nuclear Energy Power units: Watts (J/s) Power = Rate of Energy Flow Pav = ∆E ∆t

Handy Eq. 2 vx2 = vx0 v 2 = v02 − 2g∆y

2 − 2g∆y vy2 = vy0

9

Vector Velocity vx = v0 cos(θ) 2

vy = v0 sin(θ)

Centripetal means towards the center of the circle 2 2 acentrip = vr , Fcentrip = mv r T = 2πr/v (T is period of motion)

Circular Motion