...General Physics 2
Name: Grade 8. Section: Score: School: Teacher: Subject: General PMsics 2 LAs Writer: JAN JEFFREY R. CAMIFJA Content Editor: Learning Topic: Relativistic Momentum and Energy: Quarter 4-Weelr 7 LAS 1 Learning Targets: Calculate kinetic energy. rest energy. momentum. and speed or ob'pcts moving with speeds comparable to the speed of light. STEM_GP12MP-lVg-42 Relerence(s): Walker, Jearl. David Halliday. and Robert Resnick. 2004. Fundamentals Of Physics. 71h ed. New Jealsey: John lMley and Sons Inc.. pp.12701274. Relativistic Momentum and Energy Relativistic Momentum (p) It is just classical momentum multiplied by the relativistic lactor (y). p = rum where m is the rest mass of the object. 14 is its velocity relative to an observer. and the relativistic factor. _ 1 ' g 1' F : 21' 0 02:: 0.4: 0.61: 0.9.: 1.0: Relativistic momentum has the same intuitive tool as classical momentum. M \"(We It is greatest for large masses moving at high velocities. but. because of the 719.". 1_ nemm maul..." factor (3:), relativistic momentum approaches innity as velocity (it) approaches infinity 3 the velocity at approaches speed of light (a). (See Figure 1) This is another indication that an object with mass cannot reach the speed of light. If it did. its momentum would become infinite. an unreasonable value. an object approaches the speed of light. Example: An electron. which has a mass of 9.11 x 10'3' kg. moves with a speed of 0.750c. Find its relativistic momentum. Given: Solution: \"=9\" x1OG'kg m u 9.11x10-31 0.750 3.0011097" u=0.7506 P= ' =w 3.10x1o~=2kgm/5 \"2 r1 (0.75:ch2 172 T Relativistic Energy The first postulate of relativity states that the laws of physics are the same in all inertial frames. Einstein showed that the law of conservation of energy is valid relativistically, it we dene energy to include a relativistic factor. It can be summarized by the equation below: Total Energy (E) Klnotlc Energy (IQ Rest Energy Energy (E4) is delined as: is defined as: is defined as: 5:}!ch K=ymc'-mc2 + 3:ch The Relationship of relativistic momentum and energy can be defined by: E' 2 (pa? + (mc' )1 Example: An electron in a television picture tube typically moves with a speed u = 0.25s. Find its total energy and kinetic energy in electron volts (Eu = 0.511 MeV). Given: Solution: E9 = 0.51 1 MGV 2 u = 0.25:.- E =m'c 2 = E 2 = 'j% = 0.528 MeV K: E- E9 = 0.523 MeV -o.511 MeV u u 1 --L' .. '17 '17 0.017 MeV Activity: Solve the following problems. Use the rubrics as your guide in presenting your solution (reler to attachment A1 at the next page). 1. An electron. which has a mass of 8.45 x 10-31 kg. moves with a speed of 0.45c. Find its relativistic momentum and find the percentage increase of its relativistic momentum from its classical momentum. 2. An electron in a television picture tube typically moves with a speed it = 0.25s. Find its total energy and kinetic energy in electron volts {Ea = 0.385 MeV) A.1 Rubric: for the Activity Fully meet the Minimally meet the Did not meet the expectations expectations expectations Solution Correct and complete Incomplete solution with Wrong solution solution with no minimal mathematical errors . mathematical errors (1 pelnt) (2 points) (3 points) Final Answer Final answer is correct Makes a small computation Answer is incorrect. or and labels it correctly. error or did not label it student does not have a correctly. nal answer. (2 points) (1 point) (0)
