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