# AP Physics 1: 3.3 Fields in Space

Maybe if the dinosaurs had paid more attention in AP Physics, they could've figured out a way to avoid that pesky extinction problem. Oh well. Solve this question in fond memory of all the dinosaurs.

 AP Physics 1 Fields in Space Language English Language Science Practice 3 Engaging in scientific questioning

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00:22

thousand kilometers away from the center of the earth

00:25

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

00:30

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

00:36

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

00:39

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

00:44

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

00:48

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

00:51

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

00:59

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

01:03

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

01:08

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

01:12

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

01:15

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

01:20

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

01:25

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

01:29

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

01:35

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

01:40

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

01:43

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

01:50

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

02:00

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