# Velocity & Acceleration

Mechanics

Nov 14, 2013 (4 years and 6 months ago)

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Velocity & Acceleration

M
echanics

-

the study of the motion of
objects. we focus on the language, principles,
and laws that describe and explain the motion
of objects

Kinematics

is the science of describing the
motion of objects using words, diagrams,
numbers, graphs, and equations.

Kinematics is a branch of mechanics.

The goal of any study of kinematics is to
develop sophisticated mental models that
serve to describe (and ultimately, explain)
the motion of real
-
world objects.

Avoid memorizing the information; and avoid
abstracting the information from the physical
world that it describes and explains.

Rather, contemplate the information, thinking
about its meaning and its applications.

your efforts should center on internalizing the
meaning of the information.

W
e will investigate the words used to describe
the motion of objects.

scalars
,
vectors
,
distance
,
displacement
,

speed
,
velocity

and
acceleration
.

These words are used with regularity to
describe the motion of objects. Your goal
should be to become very familiar with their
meaning.

Scalars

are quantities that are fully described by a
magnitude

(or numerical value) alone.

Vectors

are quantities that are fully described by both a
magnitude
and a direction
.

5
m

30
m/sec, East

5
mi., North

20
degrees Celsius

256
bytes

4000
Calories

Scalar

Vector

Vector

Scalar

Scalar

Scalar

Speed =

Distance

Time

Velocity=

Displacement

Time

A jogger has jogged 400. meters in 75
seconds. What is the jogger’s average
speed?

Speed = Distance/Time

Speed = 400. m/75 seconds

Speed = 5.3 m/s

Distance:
how much ground an object
has covered during its motion.

Displacement:
the object's overall
change in position.

A plane is traveling north with a velocity
of 502 m/s. How long will it take to travel
3200 meters?

Velocity = Displacement/Time

Time = Displacement/Velocity

Time = 3200 m /502 m/s

Time = 6.4s

Discuss and write in complete
sentences

Why do we use velocity and displacement
together or speed and distance together?

Compare and contrast

velocity and
displacement are vectors

speed and
distance are scalars

What is the
resulting
displacement

and
distance

of travel?

The diagram shows several
of coach's positions at
various times.

At each marked position,
the coach makes a "U
-
turn"
and moves in the opposite
direction.

In other words, the coach
moves from position A to B
to C to D.

Distance is a
scalar quantity

that refers to
"how much ground an object has covered"
during its motion.

Displacement is a
vector quantity

that refers
to "how far out of place an object is"; it is the
object's overall change in position.