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A modeling approach to the 8.01 final exam equation sheet.

Page Contents

Interactions

General Definitions

Work
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ W = \int_

Unknown macro: {r_0}

^

Unknown macro: {r_f}

\vec

Unknown macro: {F}

\cdot d\vec

Unknown macro: {r}

]\end

Potential Energy
Unknown macro: {latex}

\begin

Unknown macro: {large}

[\Delta U = -W_

Unknown macro: {rm conservative}

= -\int_

Unknown macro: {A}

^

Unknown macro: {B}

\vec

Unknown macro: {F}

_

Unknown macro: {c}

\cdot d\vec

Unknown macro: {r}

]\end

Power
Unknown macro: {latex}

\begin

Unknown macro: {large}

[P = \vec

Unknown macro: {F}

\cdot\vec

Unknown macro: {v}

\qquad \qquad P_

Unknown macro: {rot}

=\frac{dW_{rot}}

Unknown macro: {dt}

= \tau_

Unknown macro: {S}

\omega]\end

Impulse
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ I = \int_

Unknown macro: {t=0}

^

Unknown macro: {t=t_f}

\vec

Unknown macro: {F}

(t)\:dt ]\end

Torque
Unknown macro: {latex}

\begin

Unknown macro: {large}

[\vec

Unknown macro: {tau}

_

Unknown macro: {S}

= \vec

Unknown macro: {r}

_

Unknown macro: {PS}

\times\vec

Unknown macro: {F}

_

Unknown macro: {P}

\qquad \qquad |\vec

_

Unknown macro: {S}

| = |\vec

Unknown macro: {r}

_

Unknown macro: {PS}

||\vec

Unknown macro: {F}

_

Unknown macro: {P}

| \sin\theta = r_

Unknown macro: {perp}

F = r F_

]\end

Net Torque
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \sum_

Unknown macro: {i}

\vec

Unknown macro: {tau}

_

Unknown macro: {S,i}

= \vec

Unknown macro: {r}

_

Unknown macro: {S,cm}

\times \sum_

\vec

Unknown macro: {F}

_

Unknown macro: {i}

^

Unknown macro: {:ext}

+ \sum_

\vec

Unknown macro: {r}

_

Unknown macro: {cm,i}

\times \vec

_

Unknown macro: {i}

^

Unknown macro: {:ext}

]\end

Specific Interactions

Gravity – Universal
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \vec

Unknown macro: {F}

_

Unknown macro: {12}

= - G\frac{m_

Unknown macro: {1}

m_{2}}{r_

^{2}}\hat

Unknown macro: {r}

_

Unknown macro: {12}

\qquad\qquad U_

(r) = - G\frac{m_

Unknown macro: {1}

m_{2}}{r_{12}}]\end

Gravity – Near Earth
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ F = mg \mbox

Unknown macro: { (directed straight downward)}

\qquad \qquad U = mgy ]\end

Contact Force
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \vec

Unknown macro: {F}

_

Unknown macro: {contact}

= \vec

Unknown macro: {N}

+ \vec

Unknown macro: {f}

]\end

Friction – Static
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ 0 \le f_

Unknown macro: {s}

\le f_

Unknown macro: {s,max}

= \mu_

N \mbox

Unknown macro: { (directed opposite net force neglecting friction)}

]\end

Friction – Kinetic
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ f_

Unknown macro: {k}

= \mu_

N \mbox

Unknown macro: { (opposes motion with respect to the surface)}

]\end

Springs
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ F = k|\Delta x| \mbox

Unknown macro: { (restoring)}

\qquad \qquad U = \frac

Unknown macro: {1}
Unknown macro: {2}

k x^

]\end

System Characteristics

Center of Mass
Unknown macro: {latex}

\begin

Unknown macro: {large}

[\vec

Unknown macro: {R}

_

Unknown macro: {cm}

= \frac

Unknown macro: {1}

{m^{total}} \sum_

Unknown macro: {i=1}

^

Unknown macro: {i=N}

m_

Unknown macro: {i}

\vec

Unknown macro: {r}

_

\rightarrow \frac

{m^{total}} \int_

Unknown macro: {body}

dm\: \vec

Unknown macro: {r}

]\end

Velocity of Center of Mass
Unknown macro: {latex}

\begin

Unknown macro: {large}

[\vec

Unknown macro: {V}

_

Unknown macro: {cm}

= \frac

Unknown macro: {1}

{m^{total}} \sum_

Unknown macro: {i=1}

^

Unknown macro: {i=N}

m_

Unknown macro: {i}

\vec

Unknown macro: {v}

_

\rightarrow \frac

{m^{total}} \int_

Unknown macro: {body}

dm\: \vec

Unknown macro: {v}

]\end

Momentum
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \vec

Unknown macro: {p}

= m\vec

Unknown macro: {v}

\qquad \qquad \vec

^

Unknown macro: {:sys}

= \sum_

Unknown macro: {i=1}

^

Unknown macro: {N}

m_

Unknown macro: {i}

\vec

Unknown macro: {v}

_

]\end

Translational Kinetic Energy
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ K = \frac

Unknown macro: {1}
Unknown macro: {2}

mv^

\qquad \qquad \Delta K = \frac

Unknown macro: {2}

mv_

Unknown macro: {f}

^

- \frac

Unknown macro: {1}
Unknown macro: {2}

mv_

Unknown macro: {0}

^

]\end

Period
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ T = \frac

Unknown macro: {2pi}
Unknown macro: {omega}

]\end

Frequency
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ f = \frac

Unknown macro: {1}
Unknown macro: {T}

= \frac

Unknown macro: {omega}
Unknown macro: {2pi}

]\end

Moment of Inertia
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ I_

Unknown macro: {S}

= \int_

Unknown macro: {body}

dm\:r_

Unknown macro: {perp}

^

Unknown macro: {2}

\qquad\qquad I_

=md^

Unknown macro: {2}

+ I_

Unknown macro: {cm}

\mbox

Unknown macro: { (Parallel Axis Theorem)}

]\end

Rotational Kinetic Energy
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ K = \frac

Unknown macro: {1}
Unknown macro: {2}

I\omega^

]\end

Total Kinetic Energy
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ K^

Unknown macro: {total}

= \frac

Unknown macro: {1}
Unknown macro: {2}

m^

v_

Unknown macro: {cm}

^

Unknown macro: {2}

+ \frac

Unknown macro: {1}

I_

\omega^

Unknown macro: {2}

]\end

Angular Momentum (Point Particles)
Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \vec

Unknown macro: {L}

_

Unknown macro: {S}

= \sum_

Unknown macro: {i}

\vec

Unknown macro: {r}

_

Unknown macro: {S,i}

\times m_

\vec

Unknown macro: {v}

_

Unknown macro: {i}

]\end

Angular Momentum (System)
Unknown macro: {latex}

\begin

Unknown macro: {large}

[\vec

Unknown macro: {L}

_

Unknown macro: {S}

= \vec

Unknown macro: {r}

_

Unknown macro: {S,cm}

\times m^

Unknown macro: {total}

\vec

Unknown macro: {v}

_

Unknown macro: {cm}

+ I_

\vec

Unknown macro: {omega}

]\end

Models

Momentum and Impulse

Unknown macro: {latex}

\begin

Unknown macro: {large}

[ \vec

Unknown macro: {F}

_

Unknown macro: {ext}

^

Unknown macro: {:total}

= \frac{d\vec

Unknown macro: {p}

^{\:sys}}

Unknown macro: {dt}

\qquad \qquad \Delta \vec

= \vec

Unknown macro: {I}

]\end

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