physics
A 72.0 kg piece of a satellite left over from an explosion with zero orbital velocity in space falls from a distance of 190 above the surface of the earth down toward earth. It arrives with 29.5 Km (M="mega") kinetic energy on earth. How many MJ energy have been lost due to friction in the earth's atmosphere ? Use the exact expression for the gravitational potential energy.

What are the units of the "190" elevation from which it fell?
29.5 Km is not a measure of energy. Please copy the question more carefullyposted by drwls

190Km *
29.5 MJ *posted by marie

The gravitational potential energy change is
deltaPE = G*M*m/R + G*M*m/(R+h)
where G is the universal gravity constant, M is the mass of the earth, m is 170 kg and R is the radius of the earth (6,378,000 m). h is the initial altitude above the Earth's surface.
This can also be written
deltaPE = mgR + mgR[R/(R+h)]
= mgR{1  [1/(1 + h/R)]}
= 170kg*9.8 m/s^2*6378*10^3 m
*{1  [1  1/(1 + (190/6378))]
= 1.063*10^10*0.0289 = 3.071*10^8 J
So 307 MegaJoules of gravitational PE is lost. If the kinetic energy on arrival is 29.5 mJ, the remainder has been lost due to frictkion, and converted to heat.posted by drwls

thank you, but for some reason its wrong
posted by marie

it says "Make sure you calculate with at least 3 significant digits. Express your answer using two significant figures."
posted by marie

The above equation is all right  just make sure you use the right value for mass (72 kg; not 170). Also, make sure you convert the 190km into meterstherefore your calculations would be (190,000m/6.4e6m). If you do all the conversions right, you should get the right answer! Good luck.
posted by Anonymous
Respond to this Question
Similar Questions

math
The orbital velocity of a satellite is given by v=√GM/R+h, where G= 6.67*10^11 Nm^2kg^2, is the Universal Gravitational Constant, M=6*10^24 kg, is the mass of Earth, R=6.38*10^3 km, the orbit of the satellite, and h is 
math
The orbital velocity of a satellite is given by v=√GM/R+h, where G= 6.67*10^11 Nm^2kg^2, is the Universal Gravitational Constant, M=6*10^24 kg, is the mass of Earth, R=6.38*10^3 km, the orbit of the satellite, and h is 
PHYSICS HELP
A satellite of mass m is orbiting the earth, mass M , in a circular orbit of radius ra . Unfortunately a piece of space debris left by a passing rocket lies directly in the satellite's path. The piece of debris has the same mass m 
physics
NASA launches a satellite into orbit at a height above the surface of the Earth equal to the Earth's mean radius. The mass of the satellite is 550 kg. (Assume the Earth's mass is 5.97 1024 kg and its radius is 6.38 106 m.) (a) How 
Physics Classical Mechanics
A satellite of mass m is orbiting the earth, mass M , in a circular orbit of radius ra . Unfortunately a piece of space debris left by a passing rocket lies directly in the satellite's path. The piece of debris has the same mass m 
Physics
A satellite is placed between the Earth and the Moon, along a straight line that connects their centers of mass. The satellite has an orbital period around the Earth that is the same as that of the Moon, 27.3 days. How far away 
physics
a geosynchronous satellite orbits at a distance from earth's center of about 6.6 earth radii and takes 24 h to go around once. what distance in meters does the satellite travel in one day? what is its orbital velocity in m /s? 
physics
a geosynchronous satellite orbits at a distance from earth's center of about 6.6 earth radii and takes 24 h to go around once. what distance in meters does the satellite travel in one day? what is its orbital velocity in m /s? 
Physics
A satellite orbits at a distance from the Earth's center of abut 3.00 earth radii and takes 7.30 hours to go around once. What distance (in meters) does the satellite travel in one day? And, what is the orbital velocity (in m/s)? 
physics
Two satellites are orbiting the Earth in stable circular orbits. Satellite A has a mass m and is located at a distance 2r from the center of the Earth. Satellite B has a mass 2m and is located at a distance r from the center of