Satellites N and F have the same mass and move in circular orbits about the same planet - AQA - A-Level Physics - Question 13 - 2022 - Paper 2
Question 13
Satellites N and F have the same mass and move in circular orbits about the same planet. The orbital radius of N is less than that of F.
Which is smaller for N than... show full transcript
Worked Solution & Example Answer:Satellites N and F have the same mass and move in circular orbits about the same planet - AQA - A-Level Physics - Question 13 - 2022 - Paper 2
Step 1
A. the gravitational force on the satellite
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Answer
The gravitational force acting on a satellite in orbit is given by the formula:
F=r2GMm
where G is the gravitational constant, M is the mass of the planet, m is the mass of the satellite, and r is the distance (orbital radius) from the center of the planet. Since satellite N has a smaller radius (rN<rF), the gravitational force on satellite N is actually greater than that on F. Thus, this option is incorrect.
Step 2
B. the speed of the satellite
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Answer
The speed of a satellite in a circular orbit is determined by the formula:
v=rGM
Since satellite N has a smaller orbital radius than satellite F, its speed will be greater. This means the speed of the satellite N is not smaller than that of F. Therefore, this option is also incorrect.
Step 3
C. the kinetic energy of the satellite
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Answer
The kinetic energy (KE) of a satellite is given by:
KE=21mv2
Substituting the expression for speed into the kinetic energy formula, we find that the kinetic energy of satellite N, having a greater speed, will also be greater than that of satellite F. Hence, this option is also incorrect.
Step 4
D. the orbital period of the satellite
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Answer
The orbital period (T) of a satellite is given by:
T=2πGMr3
Since satellite N has a smaller radius (r), its orbital period will also be less than that of F. Thus, this makes D the correct answer.