A research probe records a gravitational field strength of at an altitude of above…

PHYSICS · Single correct · A Level · Physics · Fields and their consequences · Fields and their consequences

Problem

A research probe records a gravitational field strength of

6.0\,\text{N/kg}

at an altitude of

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

above the surface of an unknown planet. Later, at an altitude of

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

, the field strength is measured to be

2.0\,\text{N/kg}

. Using only these two measurements, estimate the planet’s radius. (a)

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

(b)

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

(c)

7.4\times10^{5}\,\text{m}

(d)

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