Presentation on theme: " PROGRAM OF “PHYSICS” Lecturer: Dr. DO Xuan Hoi Room 413"— Presentation transcript:
1 PROGRAM OF “PHYSICS” Lecturer: Dr. DO Xuan Hoi Room 413
2 PHYSICS I (General Mechanics) 02 credits (30 periods)Chapter 1 Bases of Kinematics Motion in One Dimension Motion in Two DimensionsChapter 2 The Laws of MotionChapter 3 Work and Mechanical EnergyChapter 4 Linear Momentum and CollisionsChapter 5 Rotation of a Rigid Object About a Fixed AxisChapter 6 Static EquilibriumChapter 7 Universal Gravitation
3 References :Halliday D., Resnick R. and Walker, J. (2005), Fundamentals of Physics, Extended seventh edition. John Willey and Sons, Inc.Alonso M. and Finn E.J. (1992). Physics, Addison-Wesley Publishing CompanyHecht, E. (2000). Physics. Calculus, Second Edition. Brooks/Cole.Faughn/Serway (2006), Serway’s College Physics, Brooks/Cole.Roger Muncaster (1994), A-Level Physics, Stanley Thornes.
5 Universal Gravitation PHYSICS IChapter 7Universal GravitationNewton’s Law of Universal GravitationKepler’s LawsGravitational Potential Energy
6 1. Newton’s Law of Universal Gravitation The Law: “Every particle in the Universe attracts every other particle with a force that isdirectly proportional to the product of their masses and inversely proportional to the square of the distance between them.”
7 Free-Fall Acceleration The force acting on a freely falling object of mass m near the Earth’s surface. Newton’s second law:(ME: Earth’s mass; RE: Earth’s radius)Object of mass m located a distance h above the Earth’s surface or a distance r from the Earth’s center:
8 EXAMPLE 1 Two objects attract each other with a gravitational force of magnitude 1.0010-8 N when separated by 20.0 cm. Ifthe total mass of the two objects is 5.00 kg, what is themass of each?
9 2. Kepler’s laws 1. All planets move in elliptical orbits with the Sun at one focal point.2. The radius vector drawn from the Sun to aplanet sweeps out equal areas in equal time intervals.3. The square of the orbital period of any planet is proportional to the cube of the semimajor axis of the elliptical orbit.T : period of revolution, a : semimajor axisa
10 CIRCULAR ORBIT : A planet of mass Mp moving around the Sun of mass MS in a circular orbit
11 EXAMPLE 2 Calculate the mass of the Sun using the fact that the period of the Earth’s orbit around the Sun is 3.156107 s and itsdistance from the Sun is 1.4961011 m.
12 3. Gravitational Potential Energy We put :In general:
13 To compare: Gravitational force near the Earth’s surface:Gravitational potential near the Earth’s surface: Elastic force :Elastic potential: Gravitational force :Gravitational potential : Coulomb force :Gravitational potential :General formula:
14 EXAMPLE 3As Mars orbits the sun in its elliptical orbit, its distance ofclosest approach to the center of the sun (at perihelion) is2.0671011 m, and its maximum distance from the centerof the sun (at aphelion) is 2.4921011 m. If the orbitalspeed of Mars at aphelion is 2.198104 m/s, what is itsorbital speed at perihelion? (You can ignore the influenceof the other planets.)Apply conservation of energy:
15 EXAMPLE 4 Escape SpeedEscape speed: The minimum speed the object must haveat the Earth’s surface in order to escape from the influenceof the Earth’s gravitational field.
16 EXAMPLE 4 Escape SpeedEscape speed: The minimum speed the object must haveat the Earth’s surface in order to escape from the influenceof the Earth’s gravitational field.