Competency #1

Answer and Explanation

The correct answer is E.

Weight is the force of gravity acting on an object (Fg). Newton's Universal Law of Gravitation states that:

NLoUG

If we wanted to know what Fg was when the Earth was spinning we would need the following information:

  1. G is a universal constant with a value of 6.67 x 10-11 N m2/kg2.
  2. If we take object one to be the earth, the mass of the earth is: 5.98 x 1024 kg.
  3. If we take object two to be you, then we need your mass (in kg), the distance between you and the earth, would be the radius of the earth, 6.38 x 106 m.

Now if the earth stopped spinning, how would any of those values change?

  1. G - a universal constant. This means it always has the same value, so it wouldn't change.
  2. The mass of the earth has to do with the amount of matter in the earth. That is the same value, weather the earth is rotating or not (think of a yo-yo. It does not change weight when you spin it).
  3. Similarly, your mass is the same whether you are spinning, running or standing still. So your mass doesn't change. The radius of the earth would not significantly change if the earth was to stop spinning (especially not in the given time of five minutes).

Therefore, none of the values change, so the Fg would be the same. Thus, your weight would not significantly change.

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