1. The document discusses the motion of objects thrown vertically upward and neglecting air resistance. 2. It states that as an object moves upward, its velocity decreases and acceleration due to gravity acts downward. At maximum height, the velocity is 0 m/s. 3. As the object falls back downward, its velocity increases in the negative direction and acceleration due to gravity continues acting downward.

1. TERMINAL VELOCITY

2. Going up?
If an object is is thrown upward
away from the surface of the earth
(and we ignore air friction)…
• As the ball is going up…
• What happens to its velocity? What Its velocity decreases. Its
direction does it act in? direction is upward
• What happens to acceleration due to It is 9.81 m/s2. It is acting
gravity? What direction does it act in? downward
• What is its velocity at the maximum 0 m/s!
height?

3. Going up?
If an object is thrown upward
away from the surface of the
earth (and we ignore air
friction)…
• As the ball begins traveling down… Its velocity increases in
the negative direction
• What happens to its velocity?
• What happens to its acceleration
due to gravity? What direction It remains at -9.81 m/s2. It
does it act in? is acting downward.

4. ACCELERATION DUE TO GRAVITY
• Negative & positive signs are
VERY important in vertical
motion
• MUST be consistent
• G is negative
• Vertical downward
displacement away from
origin is negative
• Vertical upward
displacement away from
origin is positive

5. EXAMPLE: BALL THROWN IN AIR
• Karl Malone tosses a ball straight up in the air
vertically with an initial velocity of 10.0 m/s. What
is the maximum height the ball will reach (neglect
air friction)?
Xi = 0m Vf2 = Vi2 + 2a(xf-xi)
Xf = ?
Vi = 10.0 m/s 0 = 102 + 2(-9.81)(xf -0)
Vf = 0 m/s
a= -9.81 m/s2
-100 = -19.62(xf -0)
t=
xf = 5.10 m

6. EXAMPLE: BALL THROWN IN AIR
• Karl Malone tosses a ball straight up in the air
vertically with an initial velocity of 10.0 m/s. This
time, find the time it takes the ball to reach its
maximum height (neglect air friction)
Xi = 0m Vf = Vi+ at
Xf = 5.10 m
Vi = 10.0 m/s 0 = 10.0 + (-9.81)t
Vf = 0 m/s
a= -9.81 m/s2
-10.0 = -9.81t
t=
t = 1.02 seconds

7. EXAMPLE: BALL THROWN IN AIR
• Karl Malone tosses a ball straight up in the air
vertically with an initial velocity of 10.0 m/s. This
time, find the final velocity of the ball, if Karl
catches the ball at the same location he threw
it(neglect air friction)
Xi = 0m Vf2 = Vi2 + 2a(xf-xi)
The velocity of an
Xf = 0 m object tossed in
Vi = 10.0 m/s
Vf2 = 10.02 + 2(-9.81)(0-0) the air will have
Vf = ? the same velocity
Vf2 = 10.02 + 0 but in the opposite
a = -9.81 m/s2
direction when it
t=
Vf = - 10.0 m/s returns to its
original posiion!!

8. EXAMPLE: BALL THROWN IN AIR
• Karl Malone tosses a ball straight up in the air
vertically with an initial velocity of 10.0 m/s. This
time, find the time it takes the ball to reach its
original position(neglect air friction)
Xi =
0m vf = vi + at
Xf =
0m
Vi = 10.0 m/s
-10.0 = 10.0 + (-9.81)t
Vf = -10.0 m/s
a = -9.81 m/s2
-20.0 = -9.81t
t=
t = 2.04 s

9. OUR DATA SO FAR…
Notice any At t = 1.02 s v = 0 m/s
patterns?v = 0 m/s
At t = 0.00 s
Vi = 10.0 m/s At t =2.04 s
v = -10.0 m/s

10. WHAT DOES THIS LOOK LIKE GRAPHICALLY?
• Graph of an object thrown vertically upward
Displacement vs. time Velocity vs. time Acceleration vs. time

11. MEASURE YOUR REACTION TIME!
• Reaction time affects your performance in a number of activities
• Today you will determine your reaction time!
1. Have a friend hold a meterstick vertically between the thumb and index finger of your
open hand. Meter stick should be held so that the zro mark is between your fingers with 1
mark above it. Do not touch meter stick, let it fall freely. Your catching hand should be
resting on a table
2. Without warning, your friend will drop the meterstick so that it falls between your thumb
and finger. Catch the meter stick as quickly as you can!
3. Record the distance the meter stick falls through your grasp. Do this five times.
4. Calculate your average reaction time from the free fall acceleration and the distance you
measure.