Question

द एप्लीकेशन ड्यू टो ग्रेविटी अट ए प्लेस जीरो पॉइंट 2 मीटर पर सेकंड स्क्वेयर फाइंड द हाइट ऑफ द सरफेस ऑफ द अर्थ रेडियस ऑफ द अर्थ 16 किलोमीटर ​

Answer 1

Answer:The Force of Gravity Any two objects that have mass attract each other with a force we call gravity. You probably never noticed this for small objects, because the force is so weak. But the Earth has lots of mass, and so it exerts a big gravitational force on you. We call that force your weight. The fact that gravity is actually a force of attraction is not obvious. Prior to the work of Isaac Newton, it was assumed that gravity was simply the natural tendency of objects to move downward. If you weigh 150 lb, and are sitting about 1 meter (3.3 feet) from another person of similar weight, then the gravitational force of attraction between the two of you is 10-7 lb. This seems small, but such forces can be measured; it is about the same as the weight of a flea. You weigh less when you stand on the Moon, because the force of attraction is less. If you weigh 150 lb on the Earth, you would weigh only 25 lb on the Moon. You haven’t changed (you are made up of the same atoms), but the force exerted on you is different. Physicists like to say that your mass hasn’t changed, only your weight. Think of mass as the amount of material, and weight as the force of attraction of the Earth (or whatever other planet or satellite you are standing on). Mass is commonly measured in kilograms. If you put a kilogram of material on the surface of the Earth, the pull of gravity will be a force of 2.2 lbs. So a good definition of a kilogram is an amount of material that weighs 2.2 lbs when placed on the surface of the Earth. That number is worth remembering.1 Go to the surface of Jupiter, and you will weigh nearly 400 lbs. On the surface of the Sun you will weigh about 2 tons, at least for the brief moment before you are fried to a crisp. But in all cases your mass will be 68 kg. The equation that describes the pull of gravity between two objects was discovered by Isaac Newton. It says that the force of attraction is proportional to the mass – double the mass and the force doubles. The force also depends on the distance. It is an inverse square law. It is inverse because when the distance gets larger, the force gets smaller. It is a square law because if you triple the distance, the force decreases by nine; if you make the distance increase by 4, then the force goes down by 16, etc. 1 A more accurate value is that there are 2.205 lb in a kilogram, and 0.4536 kg in a pound, but don’t bother memorizing these more precise numbers. –1–

The Equation of Newton’s Law of Gravity “Newton’s Law of Gravity” gives the gravity force between two objects with masses m and M separated by distance r: FGmM r2 G is called the Gravitational Constant, and has the value 6.671011 N  m2kg2 (N is for Newton, the physicists’ unit of force)or 1.51011lbm2kg2.  Let’s go back to the example given in the text: two 150 lb people separated by 1 meter. 150lb The mass of each person is 2.2 lb  68kg. Putting these into the formula gives   kg F1.51011lbm2kg2 (68kg)2 107 lb.  (1m)2 Newton’s Law of Gravity actually gives the force only between two small objects. If one of the objects is a sphere (such as the Earth) then it turns out that you can still use the formula, but you must use the distance to the center of the sphere as the value for r. As an example, let’s put in numbers for a 1 kg object sitting on the surface of the Earth. Then the force of attraction is given by the gravity equation with m = 1 kg, M = the mass  of the Earth = 61024 kg, and r = radius of the Earth (that’s the distance to the center of the sphere). This distance is r = 6371 km ≈ 6106 meters. Without plugging in the numbers, can you guess what the answer will turn out to be? Guess, and then check this footnote2 to see if you guessed correctly. Suppose you weigh 150 lbs on the Earth. Then your mass is 150lb  68kg. What will 2.2 lb kg you weigh on the Moon? We can calculate that by using Newton’s Law of Gravity, and putting in the M = the mass of the Moon = 7.31022 kg, r = the radius of the moon = 1.7 106 meters. The answer is F = 25 lb. That means you will weigh 25 lb. on the surface of the Moon. Newton’s Third Law Here is something that might surprise you: if you weigh 150 lb, not only is the Earth attracting you with a force of 150 lb, but you are attracting the Earth with a force of 150 lb too. This is an example of something called “Newton’s third law” – if an object exerts a force on you, then you exert the same force back on it. 2 The answer is 2.2 lb. Of course, that is the weight of a 1 kg object. Also, 1 newton ~ 4 1⁄2 pounds, so we could express the answer as about 1⁄2 newton.  –2–