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2. 6-2 Distance & Displacement
Identify appropriate SI units for measuring distances.
Distinguish between distance and displacement.
Calculate displacement using vector addition.
3. Measure Distance
Distance is the measure of length of any path between two
points.
The path can be a straight line.
Not always
Use the unit best suited for the distance:
Very large distance km
Mississippi River is 3780 km long.
Very small distance cm or mm
The distance a marble rolls on carpet 6 cm
Distances in betweencould be hm, dkm, m, or dm.
4. Symbols
d distance
d1 , d2
x , y , or r displacement
xi , xf , yi, andyf
m meters
m mass
5. Vector vs. Scalar
Vector
Any quantity thathas magnitude (size), units, and direction
Scalar
Any quantity that has only magnitude (size), and units, but
direction does not matter.
6. Distance vs. Displacement
Distance is the length of any path between two points.
d = |x1| + |x2|
Displacement is the direction and straight line distance between
starting point and finishing point.
x = x1+ x2
y = y1+ y2
For right triangles
r = ( x2 + y2)
Sign & direction are important!!!
7. Practice
A football player runs 25 meters up-field and is pushed back 3
meters when he is tackled. What is the players distance traveled
and displacement?
8. Practice
A pitcher throws a baseball 20 meters to the catcher and the
catcher throws the ball back to the pitcher. What is the distance
traveled and the displacement of the ball?
9. Practice
The Lone Ranger runs 5 meters east to get away from the bad guys,
but he stops when he sees more bad guys and runs 12 meters west to
hide behind a rock. What was his displacement and total distance
traveled?
10. 6-2 Summary
What is the difference between distance and displacement?
How do you find displacement?
When do you use Pythagorean theorem?
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