Mr. Rogers' Honors Physics Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Momentum (9) Energy (10) Energy (11) Heat (12) Matter (13)

Mechanical Energy and Its Conservation-- Chapter 11

Relevance: The availability and use of energy is a key factor in our standard of living.

 SC Standards : Indicators P-3.1 Apply energy formulas to determine potential and kinetic energy and explain the transformation from one to the other. P-3.2 Apply the law of conservation of energy to the transfer of mechanical energy through work. P-3.3 Explain, both conceptually and quantitatively, how energy can transfer from one system to another (including work, power, and efficiency). P-3.4 Explain, both conceptually and quantitatively, the factors that influence periodic motion. P-3.5 Explain the factors involved in producing a change in momentum (including impulse and the law of conservation of momentum in both linear and rotary systems). P-3.6 Compare elastic and inelastic collisions in terms of conservation laws.

 Practice Test Study Guide
 Objectives
 Essential Question: What is energy?

Linear and Rotational Kinetic Energy

1. State that kinetic energy cannot be negative.

2. Solve problems in which work = change in kinetic energy.

3. Demonstrate that while momentum is conserved, kinetic energy is not conserved in an inelastic collision.

4. State the mathematical definition of rotational kinetic energy.

K = 1/2 I w2

5. State that the total kinetic energy of an object is the sum of rotational and linear kinetic energies, because energy is a scalar. Note: rotational and linear momentum cannot be added together.

6. Demonstrate that while momentum is conserved, kinetic energy is not conserved in a spinning ice skater problem.

Homefun (formative/summative assessment): Read sections 11.1, problems 1, 2 page 287

 Formative Assessment: Physics Investigation Title Video Analysis of an Elastic Collision Research Question Determine if both momentum and kinetic energy are conserved in elastic collisions of 2 carts on a track. Background Physics has 2 simplified methods of modelling collisions that can be used to analyze real world conditions: elastic and inelastic models. Both contain the simplifying assumption that fricition forces are negligible. Momentum is conserved in both cases and kinetic energy is conserved for elastic models. Hypothesis If a video analysis of the collision indicates a negligible loss of kinetic energy and momentum in the collision then it can be reasonably modeled as elastic. Data, Calculations Using Logger Pro software, perform video analysis on the elastic collision video with equal mass in the Advanced Physic --Mechanics folder. Make a table and report velocities, kinetic energies, and momentums for the carts both before and after the collisions, calculate the % momentum and % kinetic energy lost during the collision. Conclusions Answer the research question, discuss sources of error and possible improvements. Follow up Questions Deliverables Lable your Logger Pro video analysis file "elastic momentum analysis " and save it in the honors physics folder in your virtual student hard drive. Turn in a hand-written copy of the above data table with your conclusion Resources/Materials Logger Pro software and video files.

 Formative Assessment: Physics Investigation Title Video Analysis of an Inelastic Collision Research Question Determine if both momentum and kinetic energy are conserved in an inelastic collision of 2 carts on a track. Background Physics has 2 simplified methods of modelling collisions that can be used to analyze real world conditions: elastic and inelastic models. Both contain the simplifying assumption that fricition forces are negligible. Momentum is conserved in both cases and kinetic energy is conserved for elastic models. Hypothesis If a video analysis of the collision indicates a negligible loss of momentum in the collision then it can be reasonably modeled as obeying conservation of. Data, Calculations Using Logger Pro software, perform video analysis on both the elastic collision videos in the Advanced Physics--Mechanics folder. Make a table and report velocities, kinetic energies, and momentums for the carts both before and after the collisions, calculate the % momentum and % kinetic energy lost during the collision. (Note: kinetic energy loss should be high in an inelastic collision.) The left cart mass = 1.043 kg, the right cart mass = 0.514 kg Conclusions Answer the research question, discuss sources of error and possible improvements. Follow up Questions Deliverables Lable your Logger Pro video analysis file "elastic momentum analysis " and save it in the honors physics folder in your virtual student hard drive. Turn in a hand-written copy of the above data table with your conclusion Resources/Materials Logger Pro software and video files.

 Essential Question: Can kinetic energy be considered stored energy?

Potential or Stored Energy--Gravitational Potential Energy

1. Define potential energy in terms of work. Potential energy is work done against a conservative force
• Gravitational potential energy--work done against gravity
• Spring (elastic) potential energy--work done to compress or elongate a spring
1. Calculate gravitational potential energy (flat Earth model). Ug = mgh, Note that an arbitrary reference point must be selected as having zero gravitational potential energy. Depending on the reference selected, U can be negative.

2. State a condition that should be satisfied when modeling a system as though it has a constant level of mechanical energy.

No energy is lost as heat

3. Write an energy balance equation for systems that can be modelled as having constant mechanical energy (conservation of mechanical energy).

ME = K + U

Kbefore + Ubefore = Kafter + Uafter

4. Solve problem in which mechanical energy is considered to be constant.

pendulums

frictionless slopes

free fall (no air resistance)

Homefun (formative/summative assessment) problems 5, 6,7 p. 291.

 Essential Question: How have springs affected history in critical ways?

Spring or Elastic Potential Energy

Relevance: The practical understanding of spring potential energy has been a significant factor in shaping history with technologies such as bows and arrows, catapults, modern fire arms, clocks, vehicles, etc.

1. Calculate potential energy for a spring.

Us = 1/2 kx2

k= F/x , k is called a spring constant and is a measure of spring stiffness

2. Solve constant mechanical energy problems with springs.

spring launcher

spring bowling

3. Describe examples of simple harmonic motion in terms of energy

pendulum

spring and mass system

Homefun (formative/summative assessment):Section Review Problems 9, 10, 11; page 292

 Essential Question: Why have conservation of mass and conservation of energy merged into a single law?

The 1st Law of Thermodynamics--Conservation of Energy

Relevance:The 1st law of Thermodynamics is as close to absolute truth as anything in science.

1. State the 1st Law of Thermodynamics--conservation of energy.

2. Explain what is meant by rest energy.

Eo = mc2

3. Solve problems in which some mechanical energy is lost as heat.

falling with air resistance

slopes with friction

bullets

Homefun (formative/summative assessment): problems 59, 61, 74 page 273

 Essential Question: How can you best prepare for the test?

Review

Formative Assessments:

1. Work review problems at the board

2. Work practice problems.

Metacognition Problem Solving Question: Can I still work the problems done in class, several hours or days later? Some amount of repetition on the exact same problems is necessary to lock in learning. It is often better to thoroughly understand a single example of a problem type than to work example after example understanding none of them completely.

Relevance: Good test preparation is essential to performance in physics class.

Homefun (formative/summative assessment): turn in on the day stapled to the back of the test.

Summative Assessment: Unit exam objectives 1-17

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