Example B
Ben Rushin is waiting at a stoplight. When it finally turns
green, Ben accelerated from rest at a rate of a 6.00 m/s2
for a time of 4.10 seconds. Determine the displacement
of Ben's car during this time period.
Example A
Ima Hurryin is approaching a stoplight moving with a
velocity of +30.0 m/s. The light turns yellow, and Ima
applies the brakes and skids to a stop. If Ima's
acceleration is -8.00 m/s2, then determine the
displacement of the car during the skidd
The strategy for solving problems:
1. Identify and list the given information in
variable form.
2. Identify and list the unknown information in
variable form.
3. Identify and list the equation that will be used
to determine unknown information from known
Lesson 6 : Describing Motion
with Equations
1. The Kinematics Equations
2. Kinematics Equations and ProblemSolving
3. Kinematics Equations and Free Fall
4. Sample Problems and Solutions
5. Kinematics Equations and Graphs
The Big Misconception
the acceleration of a free-falling object (on earth) is 9.81 m/s2.
This value (known as the acceleration of gravity) is the same
for all free-falling objects regardless of
_
_.
_.
How Fast? and How Far?
The formula for determining the velocity of a falling object
from rest after a time of t seconds is vf = _
The distance fallen from rest after a time of t seconds is
given by the formula:
d = _
Acceleration is the rate at which an object changes its velocity.
It is the ratio of velocity change to time between any two points
in an object's path.
To accelerate at 9.81
m/s/s means to change
the velocity by
_ m/s each
second.
If the velocity and t
acceleration of gravity - _
_
_
the symbol g is used to represent the
acceleration of gravity.
g = _
The value of the acceleration of gravity (g) is different in
different gravitational environments.
On the moon, g = 1.6 m/s2
On Mercury, g = 3.7 m/s
Lesson 5 - Free Fall and the
Acceleration of Gravity
Introduction to Free Fall:
There are two important motion characteristics that are
true of free-falling objects:
_.
_.
Ticker tape trace for free
fall
Lesson 5 : Free Fall and the
Acceleration of Gravity
1.
2.
3.
4.
5.
Introduction to Free Fall
The Acceleration of Gravity
Representing Free Fall by Graphs
How Fast? and How Far?
The Big Misconception
example
Determine the displacement of the object during the time
interval from 2 to 3 seconds (Practice A) and during the
first 2 seconds (Practice B).
The shaded area is representative of the
displacement during from 0 seconds to 6
seconds. This area takes on the shape of a
rectangle:
area = base x height
The shaded area is representative of the
displacement during from 0 seconds to 4
seconds. This area
Determining the Slope on a v-t Graph
A method for carrying out the calculation is
1. Pick two points on the line and determine their
coordinates.
2. Determine the difference in y-coordinates for these two
points (rise).
3. Determine the difference in x-c
Check Your Understanding
Describe the motion, include the direction of motion (+ or
- direction), the velocity and acceleration and any
changes in speed (speeding up or slowing down) during
the various time intervals (e.g., intervals A, B, and C).
1.
A:
velocity
velocity
acceleration
acceleration
Compare direction of velocity
and acceleration _
Compare direction of velocity
and acceleration _
velocity
velocity
acceleration
acceleration
Compare direction of velocity
and acceleration _
Compare direction of
Check Your Understanding
The velocity-time graph for a two-stage rocket is shown
below. Use the graph and your understanding of slope
calculations to determine the acceleration of the rocket
during the listed time intervals.
1. t = 0 - 1 second
2. t = 1 -
Check Your Understanding
a.
b.
c.
d.
e.
f.
g.
h.
Consider the graph at the right. The object whose
motion is represented by this graph is . (include all
that are true):
moving in the positive direction.
moving with a constant velocity.
moving with a negat