Physics Chapter I -- Concepts of Motion

Motion Definition

the change of an object’s position with time

Types of Motion

• Linear

• Circular

• Projectile

• Rotational

Trajectory Definition

the path along which an object moves

Translational Motion Definition

Motion of an object along a trajectory

Rigid Body Definition

An object whose size and shape do not change as it moves

Kinematics definition

The mathematical description of motion

What word describes when Δx (distance) is the same over Δt?

constant

The angles of a triangle add up to:

180 degrees

Pythagorean Theorem

a² + b² = c²

Trig Identities:

sin θ = opp./hyp. = y/r

cos θ = adj./hyp. = x/r

tan θ = opp./adj. = y/x

What is the equation for radians to degrees?

2π rad. = 360°

Position definition and units

Def: location of an object with respect to a chosen coordinate system (ie. x, y, r)

Units: m (ft, km, miles…)

Position vector definition and units

Def: Arrow from origin to point representing object having:

• Magnitude (how far?)

• Direction (which way?)

Units: m (ft, km, miles…)

Magnitude definition

how much is there? (length, r, quantity)

Direction definition

which way is it pointing? (angle, θ)

Scalar definition

a single number with a unit that describes a physical quantity

contain magnitude (quanity) only

Scalars can be _, _, or _

+ / - / 0

Examples of scalar properties

time, mass, temperature, distance …

Vector definition

An object having both magnitude (size or length) and direction

Vectors are represented how?

with an arrow over a letter

Time (t) information and units

Negative time can and will exist, but we tend to avoid it, as time is always moving forward

Units: s (min, hr, etc.)

Δt represents:

the elapsed time as an object moves from an initial position (i) to a final position (f)

What is the equation for Δt?

Δt = t_f - t_i

Δ represents:

a change in a quantity

Vector examples

position (‭→x), velocity (‭→v), acceleration (‭→a)

always include a ____ with a vector, as without one you are writing a magnitude (scalar)

arrow

Displacement definition

change in position with respect to a direction

Distance, d

total path length traveled (may or may not be same as displacement)A

Average speed

rate at which distance is traveled /iow/ how far something moves in a particular instant in time

Instantaneous speed

how fast something is moving at a particular instant of time

velocity def

rate at which distance is traveled in a specific direction

Average speed depends on..

path

Average velocity depends on

initial and final position

In 1D with no changes in direction: speed avg =

|Vavg|

Acceleration

time rate of change of velocity