Ch1: Kinematics and Dynamics

Metric System

MKS (m, km, s) → SI units

CGS (cm, g, s)

Force (F)

Newton (kg·m/s^2)

Work and Energy

Joule (kg·m^2/s^2)

Power

Watt (kg·m^2/s^3)

Length: Angstrom (A)

10^-10 m

Length: Nanometre (nm)

10^-9 m

Energy: Electron-Volts

1\.6E-19 J

Vectors

Mag and direction

Displacement, velocity, acceleration, force

Scalars

Mag only

Distance, speed, energy, pressure, mass

Resultant Vector

Vector sum

Vector Components

Perpendicular parts of vector (vector as hypotenuse)

Vector Addition

Add x- and y- components

Find mag with pythagorean

Find direction with tan-1

RH Rule

Thumb: A

Fingers: B

Palm: C

Displacement (d)

Vector

Does not consider path taken

Distance (d)

Scalar

Consider path taken

Velocity (v)

Vector

Displacement/time

Same dir as displacement

Speed (v)

Scalar

Distance/time

Instantaneous Speed

= Instantaneous Velocity mag

Average Speed

Not always = Instantaneous Velocity mag

Force

Vector

Potential to cause acceleration

Measured in newtons

Gravity

Attractive force between matter

Friction

Force opposing movement

Static Friction (fs)

Between stationary object and surface

Range of values

Kinetic Friction (fk)

Between sliding object and surface

Constant value

Friction Coefficients

static > kinetic

Mass (m)

Scalar

Measure object inertia (amount of matter)

Independent of gravity

Weight (Fg)

Vector

Gravitational force on object at centre of mass/gravity

Acceleration (a)

Vector

Velocity change due to applied force

Instantaneous Acceleration

Tangent on vt-graph

Newton’s First Law

Law of inertia

Objects at rest or moving at constant velocity will remain unless acted on by a net external force

Newton’s Second Law

Objects accelerate when acted on by a nonzero force

Net force and acceleration in same dir

Newton’s Third Law

Every action has an equal and opposite reaction (on other object)

Physical contact necessary

Linear Motion

Velocity and acceleration parallel or antiparallel

Free Fall

a=g

Terminal Velocity

Air resistance drag force = weight

Fall at constant velocity

Projectile Motion

2D path

Velocities and accelerations in directions are independent

Inclined Planes

Divide forces into parallel and perpendicular components

Uniform Circular Motion

Instantaneous velocity tangent to circular path

Centripetal force points inwards to keep object on path

Tangential force = 0 (no acceleration)

Centripetal Acceleration

Generated by centripetal force

Keep object on path

Translational Equilibrium

Involve linear forces (no rotation)

Constant velocity or stationary

First Condition of Equilibrium

Sum of forces = 0

Rotational Equilibrium

Involve forces rotating object around fulcrum (pivot point)

Constant angular velocity or stationary

Torque (T)

Generated by force applied on lever arm

Greatest: Perpendicular force

Least: Parallel force

CW rotation: -

CCW rotation: +

Second Condition of Equilibrium

Sum of torques = 0