ShmoopTube

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Here's your shmoop du jour brought to you by mad scientists worried you're

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going mad? take a second to watch some cute cat [White cat appears]

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videos you know those always take the edge off for us alright

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Igor is working in his laboratory when he peers into his telescope and spots a

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large asteroid working feverishly he calculates that the asteroid is twenty [Asteroid and earth collision drawing]

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thousand kilometers away from the center of the earth

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what's the magnitude of gravitational force that the earth exerts on the

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asteroid huh and here the potential answers....... Igor is stressed but we

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can't blame him, there's an asteroid out there and he needs to make sure [Asteroid heading towards Earth]

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everything stays groovy here on earth now in order to answer this question we

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need to remember the formula to figure out gravitational force that equation

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goes a little something like this gravitational force is equal to the [Gravitational force equation appears]

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gravitational constant G times the mass of the larger object M divided by the

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square of the distance between the objects that distance here is the radius

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which is shown as R in the equation right there so GM over R squared now the

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question doesn't tell us what the mass of the earth is the only number we know

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for sure is the distance between the asteroid and the center of the earth

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which is 20,000 kilometers so we need to square that number in order to calculate

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the gravitational force but wait we need to convert those kilometers into meters

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we've got to use standard units because well they're standard for a reason [standard units appear]

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20,000 kilometers is 20 million meters and 20 million squared is 400

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quadrillion so the correct answer here is D) and boy that's a whole lot of

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meters now to answer question like this we need to memorize the equation there's [Boy's head opens and equation appears]

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no way around it people now listen carefully...G equals GM over R squared G

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equals GM over R squared...... G equals GM over R squared

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and now we're starting to understand why scientists go mad

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