Sample Problem Force And Motion 11

Sample Problem Force And Motion 11

Igor is a cosmonaut-engineer on the International Space Station, in a circular orbit around Earth, at an altitude h of 520 km and with a constant speed v of 7.6 km/s. Igor’s mass m is 79 kg.

SOLUTION: The Key Idea here is that Igor is in uniform circular motion and thus has a centripetal acceleration of magnitude. The radius of Igor’s  motion , where R£ is Earth’s radius .

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This is the value of the free-fall acceleration at Igor’s altitude. If the were lifted to that altitude and released, instead of being put into  orbit there, he would fall toward Earth’s center.

SOLUTION: There are two Key Ideas here. First, there must be a centripetal
force on Igor if he is to be in uniform circular motion. Second, that force is the gravitational force on him from Earth.

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If Igor were to stand on a scale placed on the top of a tower with height h = 520 km, the scale would read 660 N.

 

 

 

 

 

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