Download scalar: quantity described by magnitude (size) only vector: quantity

Unit I: Motion
Subunit A: Constant Velocity
Chapter 2 Section 1 Texas Physics p. 38-45
Equations
Variables, Units
NOTES:
scalar: quantity described by magnitude (size) only
vector: quantity described by both magnitude AND direction
Unit I-A Objectives
What you should know when all is said and done
1. You should distinguish between a scalar and a vector:
a. know the difference between distance and displacement.
b. know the difference between speed and velocity.
c. know the difference between average and instantaneous speed and velocity.
2. You should be able to determine the average velocity of an object in two ways:
a. determining the slope of an x vs t graph.
b. using the equation v = Δx/Δt
3. You should be able to determine the displacement of an object in two ways:
a. finding the area under a v vs t graph.
b. using the equation Δx = vt
4. Given an x vs t graph, you should be able to:
a. describe the motion of the object (starting position, direction of motion, velocity)
b. draw the corresponding v vs t graph
c. determine the average velocity of the object (slope).
d. write the mathematical model which describes the motion.
5. Given a v vs t graph, you should be able to:
a. describe the motion of the object (direction of motion, how fast)
b. draw the corresponding x vs t graph
c. determine the displacement of the object (area under curve).
d. write a mathematical model to describe the motion.
Unit I: Motion
Subunit B: Constant Acceleration
Chapter 2 Sections 2 and 3 Texas Physics p. 47-63
Equations
(figure 2.6 p.56)
NOTES:
Method for problem solving
G:
U:
E:
S:
S:
Variables, Units
(ch 2 Summary p.72)
Unit I-B Objectives
What you should know when all is said and done
1. Given a x vs. t graph, you should be able to:
a. describe the motion of the object (starting position, direction of motion, velocity)
b. draw the corresponding v vs. t graph
c. draw the corresponding a vs. t graph
d. determine the instantaneous velocity of the object at a given time
2. Given a v vs. t graph, you should be able to:
a. describe the motion of the object (direction of motion, acceleration)
b. draw the corresponding x vs. t graph
c. draw the corresponding a vs. t graph
d. write a mathematical model to describe the motion
e. determine the acceleration
f . determine the displacement for a given time interval
3. You should be able to determine the instantaneous velocity of an object in three ways:
a. determining the slope of the tangent to an x vs. t graph at a given point.
b. using the mathematical model vf = at + vi
c. using the mathematical model vf2 = vi2 + 2ax
4. You should be able to determine the displacement of an object in three ways:
a. finding the area under a v vs. t curve
b. using the mathematical model x = ½ at2 + vit
c. using the mathematical model vf2 = vi2 + 2ax
5. You should be able to determine the acceleration of an object in five ways:
a. finding the slope of a v vs. t graph
b. using the mathematical model a = v/t
c. rearranging the mathematical model x = ½ at2 + vit
d. rearranging the mathematical model vi = at + vi
e. rearranging the mathematical model vf2 = vi2 + 2ax
Unit I: Motion
Subunit C: Two-Dimensional Motion
Ch 3 of Texas Physics p.81 - 110
Equations
NOTES:
When to Use
Unit I-C: Two-Dimensional Motion
What you should know when all is said and done
By the time you finish all labs, worksheets and related activities, you should be able to:
1. Determine which model (constant velocity or accelerated motion) is appropriate to describe
the horizontal and vertical motion of a projectile. (Chapter 3, section 3)
2. Draw a motion map for an object undergoing projectile motion, with velocity and
acceleration vectors for both dimensions.
3. Given information about the initial velocity and height of a projectile determine (Ch 3, sec 3)
a. the time of flight,
b. the point where the projectile lands,
c. velocity at impact.
4. Explain what effect the mass of a projectile has on its time of flight. (Ch 3, sec 3)
5. Use the rules of vector addition to find resultant vectors. (Ch 3, sections 1 and 2)
6. Use trigonometry to find vector magnitudes and angles, and to resolve vectors into
components. (Ch 3, sections 2 and 3)
7. Describe results of using different frames of reference and determine relative velocity.
(Ch 3, section 4)
Unit II: Newton’s Laws
Subunit A: Balanced Forces
Ch 4 of Texas Physics p. 118 - 151
Variables, Units
NOTES:
Equations
Newton's first law of motion (AKA "law of
inertia"):
An object at rest will remain at rest, an object
in motion will remain in motion, in a straight
line unless acted upon by an unbalanced
force.
Inertia: the tendency of an object to resist a
change in motion.
Force: an action that may cause a change in
an object's motion. (could be a push or a pull)
Net force: The resultant force vector (the sum
of all forces) acting on an object.
Equilibrium: when the Net force on an object
is zero.
* mass is a measure of inertia
* inertia is directly proportional to mass
* inertia depends only on mass (not on motion)
* more inertia means greater resistance to
change in motion
* change in motion = change in speed and/or
direction = change in velocity = acceleration
* recall the difference between mass and
weight:
- mass is the same everywhere in the
universe (independent of gravitational field)
- weight is directly proportional to mass, but
changes from place to place depending on the
gravitational field strength
newton's 3rd law "action reaction law"
When object A exerts a force on object B,
object B exerts a force on object A that is
equal in magnitude but opposite in direction
Why don't action reaction force pairs cancel
each other out?
--> because they act on 2 DIFFERENT
objects
net force and acceleration are both
VECTORS and therefore both have
DIRECTION
the object will accelerate in the SAME
direction as the net force!
relationships:
the object's acceleration is directly
proportional to the net force acting on it, but
inversely proportional to its mass
combine 2nd law with 1st law of inertia:
the more mass an object has, the more
inertia and therefore the greater the net force
required for a given acceleration
OR
the more mass an object has, the less its
acceleration for a given net force