Mr. Rogers' Honors Physics Syllabus 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter 2D Force(5) 2D Motion(6) Gravitation(7) Rotation(8)

Gravitation-- Chapter 7
 SC Standards : Indicators P-2.1 Represent vector quantities (including displacement, velocity, acceleration, and force) and use vector addition. P-2.7 Use a free-body diagram to determine the net force and component forces acting upon an object P-2.5 Explain the factors that influence the dynamics of falling objects and projectiles.

 Practice Test Study Guide
 Objectives
 Essential Question: What is a force field field?

Newton's Law of Universal Gravitation

1. Define the term gravity field.
2.  (gravity field) = (gravity force) (unit of mass)
3. Explain why gravity field is a vector.

4. Define Newton's Law of Universal Gravitation in mathematical form and evaluate the nature of the forces involved.

5. mathematical form: F = (G∙M∙m) / r2

M and m represent 2 point sources of mass that are being pull together by an action/reaction pair of gravity forces. While the forces are opposite in direction, each has a magnitude of F as calculated above even though one of the masses could be much larger than the other.

6. Explain the assumptions and limitations of Newton's Law of Universal Gravitation

assumes planets act as point sources of mass. The variable r in the equation is the distance between the center of mass of the 2 masses.

7. only works at or above the surface of a planet. If the equation worked inside the planet, then at the center, the gravitational attraction force would be infinity. However, at the center the force = 0.

8. Draw and compare the gravity fields for 2 different mathematical models using rays.
9. Flat Earth (useful near the surface) : F = mg

Spherical planet: F = (GMm) / r2

10. Describe the gravity field inside a hollow planet. g = zero

 Essential Question: How does gravity field vary with distance?

Applications of Newton's Law of Universal Gravitation

1. Solve inverse square law type problems using Newton's Law of Universal Gravitation.

2. Combine F = mg with the Universal Gravitation Equation to find an expression for g.

Formative assessment: Evaluate the effects on g for a planet if the mass and/or radius are altered by various factors.

mass = 5.9736 x 1024 kg

G = 6.754 x 10-11 m3/kg/s2

Homefun (formative/summative assessment): Read sections 7.1

 Formative Assessment: Physics Investigation Title Simulation of Gravity Field Using a Light Source Research Question Does light intensity of the beam from a projector follow an inverse square law relationship? Background Light intensity = (amount of light) / (unit of area) Note: the division operator or / can be verbalized as "per". Hence, Light intensity is the amount of light per unit of area. Hypothesis Form a hypothesis. Data, Calculations Calculate the relative light intensity falling on the screen at a distance from the projector. Double the distance and repeat the process. Conclusions Draw a conclusion Deliverables Hypothesis, Data, Calculations, Conclusion Resources/Materials Projector and tape measure.

 Essential Question: What is the fastest way to get from one side of the Earth to the other?

Graphing a Planet's Gravity Force

1. Graph the gravity force vs. distance from the center of a planet assuming that a tunnel exists that would allow an object to pass from one side of a planet to the other through the center of the Earth.

2. Describe the motion that would occur if an object were dropped in the tunnel, assuming no air resistance and explain how theoretically this would be an incredibly good form of transportation.

Homefun (formative/summative assessment): Read section 7.2, do Section Review Problems 7, 11 p. 178.

 Essential Question: What is a geostationary orbit and how is it used?

Orbits of Satellites

1. Calculate the weight force acting on an object in orbit. F = (GMm)/r2

Formative assessment: What is the weight of a 150 lb object 1.6 x 106meters or roughly 1000 miles above the surface of the Earth?

2. Explain why a person in orbit actually has a significant amount of weight even though they feel weightless.

3. Derive an expression for the velocity required to maintain a given circular orbit using the following models:

4.  Starting Information Final Product F = ma F = (GMm) / r2 a = v2/ r v = (GM/r)1/2

5. Derive an expression for the period of a circular orbit given the orbital velocity and radius from the center of a planet. Use the following:
6. S = d / t

period: (the time it takes to complete 1 orbit) = T

distance traveled in one orbit: (the circumference) = 2πr

 Final Product T = 2π[ r3/ (GM) ]1/2

7. Define what a geostationary orbit is and why it is of significant usefulness to humans.

8. Neglecting air resistance, explain why heavier masses do not fall at a greater rate of acceleration than lighter weight masses and why the mass of an orbiting object does not affect the conditions required for orbit.

Homefun (formative/summative assessment): problems 15, 17 p. 185; 31, 33, 37, 51, 71 p. 190 to 193

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

Review of Objectives 1- 13 (1-3 days)

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): problems 81, 89, 91, 59 pages 193-194; problems turn in on the day stapled to the back of the test.

Summative Assessment: Unit exam objectives 1-16

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