Astronomers record that an exoplanet has a radius of and that a small natural…

PHYSICS · Subjective · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

Astronomers record that an exoplanet has a radius of

9.6\times10^{6}\,\text{m}

and that a small natural satellite completes one revolution in

3.0\times10^{5}\,\text{s}

at an orbital altitude of

4.0\times10^{6}\,\text{m}

above the planet’s surface. (a) Calculate the mass of the exoplanet from the satellite data. (b) Using your result, compute the theoretical value of the gravitational acceleration at the exoplanet’s surface. (c) Spectroscopic observations indicate that the actual surface gravitational acceleration is

7.8\,\text{m\,s}^{-2}

. Compare this observed value with your theoretical result and suggest one possible physical reason for any significant discrepancy.

Related theory

Acceleration Due to Gravity (g)
Gravitational Field & Acceleration
Gravitation
Satellites & Orbital Motion
Orbital velocity and period
Earth satellites

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