Physics and MeasurementPhysics and Measurement

MeasurementsMeasurementsBasic units of measure

◦Length Meter◦Mass Kilogram (1kg = 2.2lbs)◦Weight Newton (1kg = 10N)◦Time Second

Scalar vs. VectorScalar vs. VectorScalar

◦Measurement that has magnitude (number)

◦5m

Vector◦Measurement that has magnitude

and direction◦5m, east

Scalar vs. VectorScalar vs. VectorDistance

◦Measurement of length

Displacement◦Measurement of distance in a certain

direction◦Vector measured from starting point

directly to end point

Distance vs. DisplacementDistance vs. DisplacementA person walks 2 miles North,

then 4 miles East, and finally 2 miles South.

Distance = 8 miles

Displacement = 4 miles, East

Scalar vs. VectorScalar vs. VectorSpeed

◦Amount of distance traveled in a given amount of time (m/s)

Velocity◦Speed in a direction

VectorsVectorsFor Force (weight)Ever Electric Field

StrengthAt AccelerationThe TorqueD DisplacementM MomentumV Velocity

Vector ComponentsVector ComponentsVectors can be broken down into

horizontal and vertical components

Right Triangles

θ

H

Hcosθ

Hsinθ

ExamplesExamplesFind horizontal and vertical

components

20m

30°

X

Y

X = Hcos θ

Y = Hsin θ

X = 20cos 30

Y = 20sin 30

X = 17.32m

Y = 10m

ExamplesExamplesFind horizontal and vertical

components

4.6m

60°

X

Y

X = Hcos θ

Y = Hsin θ

X = 4.6cos 60

Y = 4.6sin 60

X = 2.3m

Y = 3.98m

DirectionDirectionVectors always have a direction

N

E

S

W

DirectionDirectionWhat if you don’t know which

way is north?90°

0°

270°

180°

Standard ConventionStandard Convention

90°

0°

270°

180°

ExampleExampleA student walks 6m at 0° and

then 8m at 90°. What is the resultant displacement?

6m

8mR

R= 10m, 53°

θ