Transcript File - Mrs. Sterling

Introduction to
Kinematics Notes
What is
Kinematics?
Equations
The study of motion
The big three kinematics equations of motion
Big Dog
1
d f  d o  vot  at 2
2
Symbols
Lil Pup
Shaggy Cat
v f  vo  at v2f  vo2  2a(d f  do )
What does each symbol mean? What about units?
df = Final distance (m)
do = Original distance (m)
vf = Final velocity(m/s)
vo = Original velocity(m/s)
a = Acceleration(m/s2)
t = Time (s)
Example
The runway at Midway Airport is approximately 2000m
long. The takeoff speed of a Boeing 747 aircraft is 180
miles/hour.
a. Draw a diagram and set your origin.
0m
2000m
b. What are the knowns and unknowns? (At least 4!)
df = 2000m vf = 180 mi/hr =84.5 m/s a = ?
do =
0m
vo = 0 m/s
t= ?
c. Convert numbers into physics units.
180 mi x __1.69km__ x __1000m__ x ___1 hr_ = 84.5m/s
1 hr
1 mi
1 km
3600s
Example
d. Choose an equation with only 1 unknown value.
Big Dog
1
d f  d o  vot  at 2
2
Lil Pup
Shaggy Cat
v f  vo  at v2f  vo2  2a(d f  do )
e. Solve for the unknown.
A. Calculate the acceleration of the plane.
B. Calculate how much time the plane has to take off.
C. How would these values be different if the plane
accelerated faster?
A.) Shaggy Cat:
84.52 = 02 + 2a(2000-0)
7140.25 = 0 + 2a(2000)
7140.25 = 4000a
1.79 m/s2 = a
B.) Lil Pup:
84.5 = 0 + 1.79t
84.5 = 1.79t
47.2 s = t
Example
d. Choose an equation with only 1 unknown value.
Big Dog
1
d f  d o  vot  at 2
2
Lil Pup
Shaggy Cat
v f  vo  at v2f  vo2  2a(d f  do )
e. Solve for the unknown.
A. Calculate the acceleration of the plane.
B. Calculate how much time the plane has to take off.
C. How would these values be different if the plane
accelerated faster?