Need some quick physics 110 help

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When an object weighing 100 pounds on Earth's surface is moved to 4,000 miles above, its weight decreases due to the inverse square law of gravitation, resulting in a weight of 25 pounds. The calculation involves using the formula f=Gm1m2/r², where the distance r is squared. For the second scenario, moving the object to a planet with five times the radius results in a weight of 8 pounds, calculated by adjusting the gravitational force based on the new radius. Both calculations confirm the effects of distance and planetary size on weight. The discussion emphasizes the application of gravitational principles in determining weight changes.
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this should be obvious, but I'm a little confused. Question is, ' If an object weight 100 pounds on the Earth's surface (4k miles from the center), is moved to 4000 miles above the surface. How much does it weigh?'

f=Gm1m2/r2, so you would square the r, which means you would divide Gm1m2 by 4 correct? So 25 pounds?

2.) An object on the surface of Earth that weighs 100 pounds is moved to a planet with 5x the radius and that is 2x as large, how much does the object weigh?

so it would be Gm1m2/r2= 100 lbs.

G(2)m1m2/52= 2/25 = 1/12.5.-- 100 * 1/12.5 = 8 lbs.

right?
 
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It looks all right.
 
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