PS3+(9-11)+-+8

**Students demonstrate an understanding of forces and motion by…**

8a predicting and/or graphing the path of an object in different reference planes and explain how and why (forces) it occurs.

8b using modeling, illustrating, graphing explain how distance and velocity change over time for a free falling object.

Quick list of subtopics:

 * position || position vs time graph || kinematic equations (constant acceleration) ||
 * distance || physical significance of slope ||  ||
 * speed || velocity vs time graph ||  ||
 * velocity || acceleration vs time graph ||  ||
 * acceleration ||  ||   ||

A detailed list of what students should be able to do as evidence that they understand motion:
To predict or graph the motion of objects, students must be able to apply equations of motion (prediction) and construct motion graphs. In 8b, these skills are applied to explain free fall. Two dimensional motion, including projectile motion is expressed as an extension in the GSEs.

To be able to describe, predict, and graph motion, students should to be able to:
 * Empirically associate a speed with a particular way of travel (e.g. walking, running, or skipping) and use the equation D=s*t to determine an unknown distance trip time and speed.
 * Measure and report values of position and time. This includes measuring small distances using a meter-stick as well as larger distances. Students should be able to determine the precision with which they should report these measurements. Students should be able to measure time with a stopwatch.
 * Define velocity as how an object's position changes in one second. This "operational" definition is more concrete than mathematical definitions (e.g. v=∆x/∆t or rate of change of position).
 * Because velocity indicates both the speed and direction of linear motion, students should be able to relate the sign of an object's velocity to its direction of travel.
 * Because motion is often described with a variety of terms, students should be able to explain and distinguish the terms distance, displacement, location, and distance traveled in terms of position.
 * Likewise, students should also be able to explain how speed and rate are related to velocity for an object traveling at a constant velocity, either positive or negative.
 * Plot position time for an object at rest or traveling at constant velocity to the right or left.
 * Determine the slope of a (linear?) position time graph, and argue that this slope is the object's velocity.
 * Describe a particular trip given its position time graph.
 * Relate the formula for the slope of the position time graph to related equations in math: the y-intercept form of an equation of a line and the elementary form of this idea D = s*t described in the middle school GSEs.
 * Distinguish between constant and accelerated motion in terms of how each type of motion appears in position time graphs as well as how they are //sensed// by observers.
 * Define acceleration as how an object's velocity changes in one second, and identify the units of acceleration as "meters/sec per sec" or "meters/s^2." (The former pronunciation of the units for acceleration stress the fact that velocity is changing.)
 * Plot position vs. time for an object traveling with constant acceleration.
 * Describe a particular trip given its velocity time graph.
 * Determine the rate of change of a curve at a point by drawing a tangent line on the graph.
 * Predict the appearence of position, velocity, and acceleration graphs for a variety of simple motions in both positive and negative directions.
 * Use kinematic equations derived from the definition of average acceleration to solve a variety of linear motion problems where the acceleration is constant.
 * Describe what mean by a "reference frame." Distinguish between inertial and non-inertial(accelerating) reference frames.
 * Explain how to determine the velocity and acceleration of an object in any inertial reference frame given the velocity and acceleration of the object on a particular reference frame.

Explaining Motion via Forces:

 * Explain / define force.
 * Identify common forces acting on everyday objects. Represent these forces as arrows.
 * Determine the net force acting on an object.
 * Predict the motion of an object given the net force exerted on it.
 * More detail needed.1232037573

Applying Knowledge of Motion and Forces to Free Fall:
=What do students need to know before they can address these GSEs?=
 * Still needs to be done.1232037573

Students should already be able to
 * Identify and use both metric and English units of measurement for length using a ruler or measuring tape.
 * Convert between different units of measurement for both position and velocity. Students should be able to convert between metric system units as well as between English and metric system units.
 * relate commonly used metric and English units to quantities in real life, e.g. a yard is almost a meter.
 * Plot an Y vs X (this made me laugh :) only a physics teacher would write it like that) graph both by hand, calculator, and computer. Students should also be able to draw "best fit lines" through linear data.
 * do basic algebra, including isolating a particular variable in a linear equation.

=What preconceptions might students have?  (love this section, I think this is key) =

Students might think:
 * From [|Children's Ideas in Science]:
 * all motion in the same direction as indistinguishable, i.e. not consider the difference between constant velocity and constant acceleration.
 * the motion equation from algebra, D=s*t, sufficient for analyzing all motion.
 * in order for an object to have a positive acceleration, its velocity must be positive.
 * the acceleration of a vertically launched object at the top of its path is zero.
 * if an object's acceleration is zero, its velocity must be zero, and/or vice versa.
 * Hapkiewicz, A. (1992). Finding a List of Science Misconceptions. MSTA Newsletter, 38(Winter’92), pp.11-14:
 * Time can be measured without establishing the beginning of the interval.
 * The location of an object can be described by stating its distance from a given point, ignoring direction.
 * The distance an object travels and its displacement are always the same.
 * An object’s speed is the same as its velocity.
 * If an object is accelerating, then the object is speeding up.
 * An object’s acceleration cannot change direction.
 * Acceleration always occurs in the same direction as an object is moving.
 * If an object has a speed of zero (even instantaneously), it has no acceleration.

What types of NECAP questions have addressed these GSEs?  (Nice!)
include component="page" page="NECAP-Stu Prac Bklt 2008 Gr 11 - Item 11" title="NECAP Student Practice Booklet Gr 11 2008

include component="page" page="NECAP-Released Items 2008 Gr 11 - Item 4" title="NECAP Released Item Gr 11 2008 -