This document discusses relative velocity and how to solve relative velocity problems. It explains that an object's speed depends on the reference frame it is measured from. When measuring relative velocity, vectors can be added to determine the total velocity relative to a particular reference frame, such as when calculating the speed of a person walking on a bus or airplane relative to the ground. Examples are provided to demonstrate how to use vector addition to solve relative velocity problems in different scenarios.
3. What if…
You are in a bus and it has a speed of 20 m/s relative to
the street
What does relative to the street mean?
You are sitting still
What is your speed relative to the street?
Where do you measure your speed from matters
4. Reference Frame
Coordinate systems can change according to where you
are measuring from
What if you started walking towards the front of the
bus?
You can measure your speed relative to the bus and the
street
Which is higher?
5. Example
Bus traveling east 8 m/s relative to the street
You are walking 2 m/s towards the front of the bus
What is your speed relative to the street
Add vectors!
What if you were walking 2 m/s towards the back of
the bus?
8. Example
Airplane flying with a speed relative to the ground
A person walking in the airplane with a speed relative
to the plane
What is the speed of the person relative to the ground?
9. Vector Addition
What if the vectors aren’t
in a straight line?
Flying in the air, winds
don’t always line up
nicely
10. Example
Anna and Sandra are riding on a ferry boat that is
traveling east at a speed of 4.0 m/s. Sandra rolls a
marble with a velocity of 0.75 m/s north, straight
across the deck of the boat to Anna. What is the
velocity of the marble relative to the water?
