Linear Motion
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Transcript Linear Motion
Principles of Physics
motion along a straight line path, motion in
one dimension
Which way are you headed?
How far did you go?
How fast are you going?
Is your speed changing?
Velocity
Rate at which position changes
In other words, how quickly the position of an
object changes during the time interval
Measured in meters per second (miles per
hour in the USA)
v
d
t
Velocity is calculated
d
v
t
v = average velocity (m/s)
d = displacement (m)
t = time (s)
Average because we don’t know exactly what is happening
from the 1st position to the next
▪ The object could be speeding up and slowing down along the way
Vector quantity – has direction
Direction is + when right, up, north, or east
Direction is – when left, down, south, or west
Instantaneous speed = speed at any particular
point
Can be determined by speedometer, but not
d
by v
t
1.
Rick walked 50 m in 60 s. What was his average speed?
Givens:
d = 50 m
t = 60 s
v=?
v
v
d
t
d 50m
t
60s
0.833m / s
2. A car has an average velocity of 20 m/s east. How long would it take the car to
travel 85 m?
Givens:
v = 20 m/s
t=?
d = 85 m
v
d
t
d 85m
t
v 20m / s
4.25s
3. Anna watches a thunderstorm from her window. She sees the flash of a
lightning bolt and begins counting the seconds until she hears the clap of
thunder 10.0 seconds later. Assuming that the speed of sound in air is 330
m/s, how far away was the lightning bolt? (Assume that she sees the bolt
instantaneously).
Givens:
v = 330 m/s
t = 10 s
d=?
v
d
t
d vt 330m / s(10s)
3300 m