Kinematic/Free Fall
Tommy Myszka
Nick Sraga
Mike Jewell
Terms
• Speed – distance traveled in a period of
time
• Velocity- distance traveled in a period of
time in a certain direction
• Instantaneous velocity – how fast you are
traveling at a particular time
• Acceleration – change in velocity over time
Equations
• speed = distance
time
• acceleration = VF-VI
time
• velocity = displacement
time
Other important
equations
• VF2-VI2 = 2ad
• ½ at2 + VIt = d
Concepts
•
•
•
•
Initial speed always must be zero
Gravity equals -9.8 m/s/s
Free fall acceleration equals –9.8 m/s/s
As you free fall, your distance per second
increases, as does your velocity per second
Examples From the Real World
#1
Skydiving
• As you skydive,
you’re free falling
toward the earth at –
9.8 m/s/s
Examples From the Real World
#2
Rain
• As the falls it is
constantly getting
itself a bigger and
bigger velocity
towards the earth
Sample Question
• #1 A ball dropped from rest picks up speed 10 m/s.
After it falls for 4 seconds, how fast is it going?
Givens
A=10m/s
T= 4sec
Equation: a=VF-VI
T
10m/s=VF-0
4
40=VF
Answer: 40 m/s
Sample Question
• #2 A ball is thrown straight down with an initial
speed of 20 m/s. After 3 seconds how fast is it
going?
Equation: a=V -V
-9.8=V -20
F
Givens
VI=20m/s
t=3 sec
a= -9.8m/s2
I
T
29.4=VF-20
Answer: 49.4m/s
F
3
49.4=VF
Sample Question
#3 You shoot an arrow straight up at 50m/s. When
will it hit the ground?
Given
VF=0
VI=50m/s
a= -9.8
Equation: a=VF-VI
T
-9.8=0-50
-9.8t = -50
t
t= -50
-9.8
Answer: 5.1
Sample Question
#4 Wieldy Coyote runs off a 100 meter cliff while
chasing the Roadrunner. He begins to freefall.
What is his velocity when he hits the ground?
Given
D=100m
a=-9.8
VI=0
Equation: VF2-VI2=2ad
VF2-0=2(9.8)100
VF2=1960
VF= 44.2
Answer: 44.2
Quiz Questions
#1 A bullet fired horizontally at 650m/s. How
far will it go in 1.1 seconds?
Answer: 715m
#2 A base ball is hit straight up to a height of
40 meters. How fast was the ball moving
when it let the bat?
Answer: 28 m/s
Quiz Questions
#3 If a skydiver jumps out of an airplane, and
his shoot failed and hits the ground at
50m/s. How high was he when he jump?
Answer: 127.5 meters
#4 If a person jumps off a 15 meter cliff into
water. What is the persons velocity when
he hits the water?
Answer: 17.15m/s