Physics Section 3.2
Resolve vectors into their components
When a person walks up the
side of a pyramid, the motion
is in both the horizontal and
vertical directions.
A right triangle is formed by
the motion of the person.
Formulas for right triangles
examples
• A tourist walks up a pyramid. The pyramid is 60.0 m
high and 80.0 m wide. Find the displacement of the
tourist.
• Student problem: While following the directions on
a treasure map, a pirate walks 45.0 m north and then
walks 7.50 m east. What single straight line
displacement could the pirate have taken?
Components of a vector are two vectors (usually
perpendicular) that have the same total effect as the
original vector.
Breaking a vector into its components is called
resolving the vector.
• Find the vertical and the horizontal components of a
missile traveling with a velocity of 120 m/s at an angle of
30 degrees above the horizontal.
• How fast must a truck travel to stay beneath an airplane
that is moving 105 km/h at an angle of 25 degree to the
ground?
• Student problems page 92, #3,#4
It is not possible to use the Pythagorean Theorem to
find the resultant of two vectors that do not act at right
angles to each other. Instead to add the vectors, we
must find their components.
• Find the resultant of forces of 25 N at 40
degrees N of E and 15 N at 35 degrees S of E.
Example
• Find the resultant of 20.0 m/s at 28 degrees
west of north and 30.0 m/s at 45 degrees
south of west.
• Student practice worksheet
Assignment
• Page 94
• Problems 2,3,4