 |
-
Utah State Core Standards |
Background |
Author Information
Level: 9-12
Science 3640 - Physics
Utah State Core Standard: 3640-02
-
Students will investigate the laws of motion.
-
Utah State Core Objective: 3640-0204
-
Apply principles of momentum to motion.
-
Utah State Core Intended Learning Outcomes:
|
1.
|
Use Basic Science Process Skills
- Make observations and measurements (uses instruments as
appropriate).
- Make estimations and predictions based on observations and
current knowledge.
|
|
2.
|
Use Integrated Science Process Skills
- Identify variables and describe relationships between them.
- Collect and record data using procedures designed
to minimize error.
- Analyze data and draw warranted inferences.
- Construct models and simulations to describe and
explain natural phenomena.
|
|
4.
|
Demonstrate Awareness of the Social and Historical Aspects of
Science
- Recognize the personal relevance of science in
daily life.
|
|
5.
|
Understand Science Concepts, Principles, and Systems
- Know science terminology appropriate to grade level.
- Understand natural and human-produced systems in
science (appropriate to grade level):
- Explain how the parts of a system are interconnected
and function together as a unit.
- Predict how changes in one part of a system will
likely affect the rest of the system.
- Solve problems by applying science principles and
procedures.
|
|
6.
|
Communicate Effectively Using Science Language and Reasoning
- Use the language and concepts of science as a means of
thinking and communicating.
- Prepare written and oral reports describing the findings of
investigations and the reasoning which led to the
conclusions.
- Construct tables, graphs, charts, diagrams, and
models to describe and summarize data.
- Provide relevant evidence to support inferences
put forth to be accepted by others.
- Evaluate the findings and conclusions reported by
other investigators using relevant and defensible criteria.
|
-
Momentum is a concept that is often misunderstood. One common
misconception is that momentum is a force. The use of these four lessons
will allow students to explore momentum by considering the behavior of
various objects in terms of mass and velocity. The idea of momentum is
introduced as the product of mass times velocity, and is then developed to
show how momentum is conserved under a closed system.
-
Activity One: Vehicles in Motion
-
Students will investigate the concept of linear momentum as the product of
mass and velocity (mv). Mass is measured in kilograms, and velocity is
measured in meters/second. Momentum is denoted by the letter p, where
p=mv (in units of mass times velocity, kg-m/s).
-
Activity Two: Explosions
-
This activity develops the idea of conservation of momentum via an
explosion between two trucks. This allows students to discover that
momentum is conserved within a system. Each truck has zero momentum
initially and the explosion will give each truck equal momentum in
opposite directions from each other. The velocity of each object will
depend on its mass.
-
Activity Three: Collisions
-
This lab will develop the idea of how momentum and kinetic energy are
related in a collision of two trucks. There are two fundamentally
different types of collisions, elastic collisions (both system momentum
and system kinetic energy are conserved), and inelastic collisions (where
system momentum is conserved, but system kinetic energy is not conserved).
-
Activity Four: Cosmic Ray Momentum
-
Principles of momentum are applied to explain cosmic ray acceleration.
Momentum is a vector quantity, therefore consists of both magnitude and
direction, which is provided by the velocity (mass being a scalar
quantity).
When multiple particles (objects) collide, the total momentum of the
particles is the same before and after the collision. Mathematically,
this can be expressed as:
The interaction between cosmic rays and large masses (usually gas/dust
clouds) in space exhibits the same conservation of momentum observed in
Lab Three. It is conservation of angular momentum that is generally
considered, but for our purposes, angular momentum is left for future
consideration in subsequent labs. We will simply define a cosmic
ray-large mass interaction as an elastic collision.
As cosmic rays travel through space, they encounter massive objects in
their path. As they interact (collide) with these objects, the system
momentum is conserved, with the cosmic ray gaining momentum, and the large
mass losing momentum. Assuming system mass remains constant, these
interactions result in an increased velocity of the cosmic ray, and a
decreased velocity of the mass. Since the mass of the gas cloud is many
orders of magnitude larger than the mass of the cosmic ray, the velocity
loss of the large mass is scarcely noticeable. Statistically, the
velocity gain of the cosmic ray is cumulative, and given enough time for
zillions of collisions, the velocity, and hence the kinetic energy
(1/2mv2) increases immensely.
-
-
The writing for this lesson series was headed by Tom Erekson, Tom Herret and Brad
Talbert. Editing was done by Joan Young.
|
|
