Gravity's Pull - Investigating the Effects of Gravity ----------------------------------------------------- ***borrow stand scale (w. rollers) from either clinic or health/PE for use with massing & weighing labs, e.g., "How Many Newtons...?" You know you ate too much when... - your relatives [dinner guests] can't go home 'cuz they're stuck in your gravitational field! - ? [create your own punchline] == *** Make overhead transparency master, "Newton Spring Scale" (T23). *** Problem: Transparency master shows Dynes & Newtons; Ohaus spring scales show Grams & Newtons. Use overhead to demo the spring scale "readability (metric)." http://www.ohaus.com/products/glo/scripts/view/viewproduct.asp?Recno= 8003-MN&Source=2 Ohaus Pull-Type Spring Scale Order Item # 8003-MN Specifications Capacity (metric): 1000 g / 10 N Readability (metric): 25 g / 0.25 N See also, Teachers and Schools: http://www.ohaus.com/products/education/teachers.asp featuring, "Balance Tutorials" http://www.ohaus.com/products/education/tutorials.asp?source=2 "Triple Beam" is a GREAT Macromedia Flash player animated tutorial! <-- use for tchr demo "TBB Scale Reading Exercise" <-- use for student drill & practice ... plus tutorials for electronic [digital] balances Note: Mass / weight sets can be interconnected by hanging hook on top of weights from slot [groove] & hole on bottom of weights. Ohaus(R) Mass Sets http://www.ohaus.com/products/view/overview.asp?HKEY=001003002 == Do only, "Part 1: How Does Gravity Affect an Object's Weight?", RSLG pp. S25-S29. Five (5) objects to mass/weigh: wooden box w. hook (see Maria R.); 500-g hexagonal grey metal mass w. hook; 200-g round black metal mass w. hook; No. 3 lead sinker; three (3) large washers. Place all objects in wooden box for ease of distribution/collection; group no. (1-6) appears on bottom of 500-g masses. Note: Wooden boxes (with hook) available from Fisher Scientific, Cat. No. S40915. Sample Data: grey metal mass w. hook: .501 kg; 5 N; 5/.501 = 9.98 N/kg <-- good data! [the following notes excerpted from TRG, "Gravity's Pull," p. S27] [note: need lightweight plastic mesh bag for measuring weight of objects that cannot be hooked onto spring scale] "Newton's Apple" apple: mass = 100g, 0.1kg; weight = 1N; weight is ~10x > mass "For example, 1N is the force of Earth's gravity on an apple with a mass of about 0.102kg [102g]." http://en.wikipedia.org/wiki/Newton -- Elephant Facts + Gravity Calculator + Weight of a Flea http://www.nczooeletrack.org/elephants/facts.html A. African elephants are the largest land animals with body growth continuing for up to 30 years. Bulls (males) may reach a height of 9-13 feet (3-41/2 m) at the shoulder and weigh between 9,000-13,000 pounds (4,500-6,000 kg). Cows (females) are smaller in size, averaging 7-9 feet (2.5-3 m) at the shoulder and weighing between 4,500-7,000 pounds (2,200-3,000 kg). An adult elephant will be almost as tall as it is long. [add formula for force of gravitational attraction, TRG, p. T22] Gravity Calculator: http://www.shodor.org/refdesk/Resources/Models/Gravity/index.php# Calculate force of gravity (attraction) between max. size male & female elephants (6000- & 3000kg respectively) at the following distances: 1.0 m = 0.0012 N 0.1 m (1 dm) = 0.120059 N 0.01 m (1 cm) = 12.006 N 0.001 m (1 mm) = 1200.6 N Two (2) Sanford-sized people: Google Calculator: 200 lb = ? kg 200 pound = 90.718474 kilograms M1 & M2 = 91 kg 0.1 m (1 dm) = 0.0000552 N 0.01 m (1 cm) = 0.00552 N 0.001 m (1 mm) = 0.5523427 N -- 3. Force and Gravity http://www.muller.lbl.gov/teaching/Physics10/PffP_textbook/Chapter03.htm If you weigh 150 lb, and are sitting about 1 m (3.3 ft) from another person of similar weight, then the gravitational force of attraction between the two of you is 1 x 10(-7) lb. This seems small, but such forces can be measured; it is about the same as the weight of a flea. Suppose you weigh 150 lb on the Earth. Then your mass is about 68 kg (i.e. it is 150/2.2). M1 & M2 = 68 kg 1.0 m = 3.084208e-7 N <-- weight of a flea! 0.1 m (1 dm) = 0.00003084207999999999 N 0.01 m (1 cm) = 0.0030842079999999997 N 0.001 m (1 mm) = 0.3084208 N -- Earth Statistics: Mass (kg) 5.976e+24 Equatorial radius (km) 6,378.14, or 6,378,140 m F(subG) = 666.2807100656358 N <-- makes sense, at equivalence of ~1kg per 10 newtons a(sub1) = 1.1149275603507962e-22 m/s(2) a(sub2) = 9.798245736259351 m/s(2) <-- gravitational acceleration ISS orbits at ~avg. altitude of 350km Earth's radius + altitude ISS = 6,728.14 km, or 6,728,140 m new weight = 598.7634691359087 N, or ~67 N less than weight on Earth -- not exactly "weightless" -- like what's up with that?!? For the answer, see The "Weightless Astronaut" Paradox http://www.muller.lbl.gov/teaching/Physics10/PffP_textbook/Chapter03.htm Note: In this case, the term "microgravity" would be more correct than "weightless." See the following "Microgravity Calculator": http://bpesoft.com/s/wleizero/xhac/?M=g <-- Calculates % of gravity at Earth's surface. Cool! Definitions of vomit comet on the Web: The Vomit Comet was the nickname given to the KC-135 Stratotanker used by NASA's Reduced Gravity Research Program. The plane makes parabolic flight paths, thus allowing the occupants to experience reduced gravity during the parabola. By modifying the flight path, any value for the apparent gravity may be produced. In general it is used to train astronauts in zero-g maneuvers, giving them about 25 seconds of weightlessness out of 65 seconds of flight. en.wikipedia.org/wiki/Vomit_Comet 5. Sun's mass = ~2.0 x 10(30) kg [1.9891 x 10(30) kg or 332,950 Earths!] (Mass 1) = 1.9891e+30 Earth's mass = (Mass 2) 5.976e+24 Mean Earth-Sun distance = 1.496 x 10(6) km [14,960,000,000 m or 1.496 x 10(10)] Results: F(G) = 3.542663094097629e+24 N a(1) = 0.0000017810382052675226 m/s(2) a(2) = 0.5928151094540879 m/s(2) http://en.wikipedia.org/wiki/Sun Question: The Sun has a mass of 2x10(30) kg, and is 1.5x10(8) km away, while the mass of the Moon is 7.35x10(22) kg, and is 3.8x10(5) km away. Which exerts a stronger gravitational influence on the Earth? Answer: The Sun. F(G) = 2.028880969529086e+24 a(1) = 0.3395048476454294 m/s(2) [Earth] a(2) = 27603822714681.44 m/s(2) [Moon] Q. If the Sun exerts a stronger gravitational influence on the Earth than the Moon, then why does the Moon exert a greater influence on ocean tides? A. "differential gravitation" LAH For an explantation, see: http://www.badastronomy.com/bad/misc/tides.html == Activity Extension: "How Many [Fig] Newtons(R) equal one newton?" [Use as substitute for "Part 2: How Does Gravity Affect an Object's Movement?", RSLG pp. S30-32.] Award Fig Newtons as prizes for solving the problem correctly. See the following background notes ... http://www.wsanford.com/~wsanford/gr8ps/04_red/06_work_made_easy/newtons/ ... specifically ... Newtons-in-a-newton_Ver2.txt and gravitys_pull.txt (original verson of RSLG Ver.1 activity) ***Need to create "Newtons Lite" version.*** [Done.] http://www.nabiscoworld.com/newtons/ (incl. graphics and "Nutrition Facts") Varieties/NEWTONS - COOKIES - FIG NEWTONS 16oz/Nutrition Info Nutrition Facts: Serving Size 31g [2 cookies; 1 cookie = 15.5g] Servings per Container about 15 Note: 30 cookies per 16oz pkg; 16oz = 454g total weight of pkg (actually mass), according to pkg label; 453.59g or 0.45359kg (by conversion, 16oz = ? g), 465g (by calculation: 15.5 g/cookie x 30 cookies/1 = 465g). Problem: How Many [Fig] Newtons(R) equal one newton? Solution: 1. If there are 30 cookies per (16oz) pkg, then what is the mass of a single cookie, expressed in kilograms (kg)? 30 cookies (per pkg) / 15 servings = 2 cookies per serving 31g (serving size) / 2 (cookies per serving) = 15.5g per cookie 15.5g = 0.015kg <-- mass of a single cookie 2. What is weight of a single cookie, expressed in newtons (N)? 0.015kg x 9.8 m/s(2) = 0.147 kg-m/s(2) or 0.147 N <-- weight of a single cookie [Note: Focal point of Part 1 of lab activity is weight(N) is ~10x greater than mass(kg) or vice versa, i.e., mass(kg) is ~1/10 weight(N), see RSLG p. S27, e.g., 0.147N = 0.147kg-m/s(2); 0.147 kg-m/s(2) / 9.8 m/s(2) = 0.015kg] 3. How many cookies have a weight equal to one newton (1 N)? 1 N / 0.147 N/cookie = ~6.8 cookies <-- the answer! Activity Extensions ------------------- > Convert your weight from pounds (lb) to newtons (N). Conversion Factor: 1kg = 2.2 lb Dimensional Analysis: ? lb/1 x 1 kg/2.2 lb = _____ kg; _____ N > Determine your weight (in pounds & newtons) on the Moon (Note: Your weight on the Moon is ~1/6 your weight on Earth): _____ lb; _____ N -- Graphic of 16oz pkg Fig Newtons 00527cl.gif = 10.0 KB 164x164x256 Source: Varieties == http://en.wikipedia.org/wiki/Fig_Newton == ***Editorial Review*** Video is mostly fluff (LOTS of repitition). The two best scenes are: Bill's recreation of Galileo's demo (bowling ball and apple fall at the same rate); Apollo astronaut dropping a hammer and a feather on the Moon. Consider showing these two segments only. http://dep.disney.go.com/educational/store/detail?product_id=68A76VL00 Gravity (VHS) Part of Bill Nye the Science Guy Complete Series Price: $39.95 Subject Area: Science & Nature Grade Level: Primary, Intermediate, Junior High, High School Product ID: 68A76VL00 Have you ever wondered what holds the ocean on the Earth? Or what makes the Earth round? Perhaps you've thought about what holds humans to the ground? Host Bill Nye provides the explanation for these and other questions about the earth's gravity. Edition Details Release Date: 1995 Running Time: 26 minutes Format: Video Additional Features: Marc Record Available [notes from box cover (back)] Nifty questions in this episode/Awesome answers Q. What makes the Earth go around the Sun? A. Gravity keeps the Earth revolving around the Sun. Q. What is gravity? A. Gravity makes everything pull on one another (air, water, earth) toward the center of the Earth. Q. If a bowling ball and an apple are dropped at the same time from 20 meters up, which will hit the ground first? A. Both the bowling ball and the apple will hit the ground at the same time. Q. Would there be a sky without gravity? A. No! Gravity is what holds the atmosphere around the Earth.