Section 1: Measuring Motion
Key Ideas
How is a frame of reference used to describe
motion?
What is the difference between speed and
velocity?
What do you need to know to find the speed of
an object?
How can you study speed by using graphs?
Observing Motion
Visual Concept: Motion
How do we know an object has moved????
motion: an object’s
change in position
relative to a reference
point
frame of reference:
a object that we
measure from.
Observing Motion, continued
• Distance: measures the path taken.
• Displacement: is the change of an
object’s position.
– includes direction
Speed and Velocity
What is the difference between speed and
velocity?
Speed: how fast an object moves
Speed examples:
Velocity: the speed and the direction that the
object moves.
Velocity examples:
Visual Concept: Speed
Math Skills
Speed
SI unit for speed: (m/s)
constant speed:
equal distances in
equal amounts of time
Ø The cheetah, the fastest of land animals, can
run a distance of 274 m in 8.65 s at its top
speed. What is the cheetah’s top speed?
instantaneous speed:
the speed at a given
time
Math Skills: Speed
• The various types of tree sloths share the honor
of being the slowest moving mammals. An
average tree sloth moves with a speed of 0.743
m/s. How long does it take a sloth moving at this
speed to travel 22.30 m?
And Another example
Polar bears are extremely good swimmers
and can travel as long as 10 hours without
resting. If a polar bear is swimming with an
average speed of 2.6 m/s, how far will it
have traveled after 10.0 hours?
Visual Concept: Velocity
Visual Concept: Speed and Velocity
Right and up (+) and Down and left (-)
Math Skills: Velocity
The fastest crossing of the Atlantic Ocean by an
ocean liner was made on July 7, 1952. The ship, the
SS United States, traveled 4,727 km east by
northeast in 82.0 hours. Assume that the ship had
traveled the same speed, but directly east. What
would the velocity of the SS United States be in
kilometers per hour?
Math Skills: Velocity
The longest stretch of straight railroad tracks lies
across the desolate Nullarbor Plain, between the
Australian cities of Adelaide and Perth. The tracks
extend a distance of 478 km without a curve. How
long would it take a train, moving at a constant
speed of 97.0 km/h, to travel this length of track?
Graphing Motion
How can you study speed by using graphs?
distance on the y-axis
time on the x-axis.
The slope of a distance vs. time graph equals speed.
Math Skills: Velocity
The typical snail doesn’t cover very much
ground even when it is moving at its
maximum speed, which is 0.000833 m/min.
How far will a snail travel if it moves at its top
speed for 45 minutes?
Homework
Section Review 11.1
Graphing Skills
Calculating Slope:
Distance time graphs
Calculating Slope
Slope of line A?
A
B
Slope of line B?
Homework
• Graphing Motion Activity