Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Physics Force Test Mr. Lew In “The Elegant Universe”, it was said that one of the forefathers of Physics, Sir Isaac Newton, developed a law of gravity that he called the “Universal Law of Gravitation.” This law described the force of gravity that acted “in the heavens and on earth”; from the force acting on an apple falling from a tree to the forces acting between planets in the universe. His “Universal Law of Gravitation” equation is stated below: 2 " Nm % $ 2 '[kg ][kg ] Gm 1m2 # kg & F= = = [N ] 2 2 r m where: F = the force acting between the two objects m1 and m2 [N] G = Newton’s Universal Gravitational constant = 6.67 x 10-11 [Nm2/kg2] (note how small this number is…it gives you an idea why the force of gravity is so weak!!!) m1 = the mass of object 1 [kg] m2 = the mass of object 2 [kg] r = the distance between the centers of the objects [m] ! For reference, complete the following calculations: I. What is the weight in Newton of a person of mass = 90.72 [kg] on the earth using W = mg? II. If the coefficient of friction between a 1kg hockey puck and ice is 0.2, what force is needed to move the puck across the ice at a constant velocity on earth (g = 9.8 [m/s2]? Now, use “Newton’s Universal Law of Gravitation” to find the force of gravity for the following cases: Use the following values for your calculations (source: Wikipedia) Radius of earth = 6371 [km] Mass of earth = 5.97 x 1024 [kg] a. b. c. d. e. f. g. The force of gravity (weight) on a 200 lb person on the surface of the earth (90.72 [kg]) The force of gravity on the same person on an airplane at a cruising altitude of 35,000 [ft] (10,668 [m]) The force of gravity on the same person at a distance of 330 [km] above the surface of the earth (this distance is the cruising altitude of the International Space Station) The force of gravity on the same person at a distance of 6371 [km] above the surface of the earth (this distance is equal to one earth radius) The force of gravity on the same person at a distance of TWO times 6371 [km] above the surface of the earth (two earth radii) The force of gravity on the same person at a distance of THIRTY times 6371 [km] above the surface of the earth (the distance from the surface of the earth to our moon) If the coefficient of friction between a 1kg hockey puck and ice is 0.2, what force is needed to move the puck across the ice at a constant velocity AT AN ALITITUDE OF TWO times 6371 [km] above the earth?