Answer :
(a) The work necessary to bring a 101 kg object to a height of 992 km above the surface of the Earth is 986 MJ. (b) The extra work needed to launch the object into circular orbit at a height of 992 km above the surface of the Earth is 458 MJ.
To bring an object to a height of 992 km above the surface of the Earth, we need to do work against the force of gravity. The work done is given by the formula;
W = mgh
where W is work done, m is mass of the object, g is acceleration due to gravity, and h is the height above the surface of the Earth.
Using the given values, we have;
m = 101 kg
g = 9.81 m/s²
h = 992 km = 992,000 m
W = (101 kg)(9.81 m/s²)(992,000 m) = 9.86 × 10¹¹ J
Converting J to MJ, we get;
W = 986 MJ
Therefore, the work necessary to bring a 101 kg object to a height of 992 km above the surface of the Earth is 986 MJ.
To launch the object into circular orbit at this height, we need to do additional work to overcome the gravitational potential energy and give it the necessary kinetic energy to maintain circular orbit. The extra work done is given by the formula;
W = (1/2)mv² - GMm/r
where W is work done, m is mass of the object, v is velocity of the object in circular orbit, G is gravitational constant, M is the mass of the Earth, and r is the distance between the object and the center of the Earth.
We can find the velocity of the object using the formula:
v = √(GM/r)
where √ is the square root symbol. Substituting the given values, we have;
v = √[(6.67 × 10⁻¹¹ N·m²/kg²)(5.97 × 10²⁴ kg)/(6,371 km + 992 km)] = 7,657 m/s
Substituting the values into the formula for work, we have;
W = (1/2)(101 kg)(7,657 m/s)² - (6.67 × 10⁻¹¹ N·m²/kg²)(5.97 × 10²⁴ kg)(101 kg)/(6,371 km + 992 km)
W = 4.58 × 10¹¹ J
Converting J to the required units, we get;
W = 458 MJ
Therefore, the extra work needed to launch the object into circular orbit at a height of 992 km above the surface of the Earth is 458 MJ.
To know more about circular orbit here
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--The given question is incomplete, the complete question is
"(a) Calculate the work (in MJ) necessary to bring a 101 kg object to a height of 992 km above the surface of the Earth.__ MJ (b) Calculate the extra work (in MJ) needed to launch the object into circular orbit at this height of 992 km above the surface of the Earth .__MJ."--
