Answer:
The mass of the planet is M = 7.75 × 10^14 kg
Explanation:
From the Newton's law of gravitation;
F = GMm/r^2
Where
F = gravitational force
G = gravitational constant
M = mass of planet
m = mass of other object
r = radius
And note that;
F = mg = GMm/r^2
g = GM/r^2
Making M the subject of formula,
M = gr^2/G ......1
g = acceleration due to gravity in the planet.
From h = 0.5gt^2
g = 2h/t^2
given; h = 1.40 m
t = 29.4s
g = (2×1.4/29.4^2)m/s
Circumference of the planet is = 2πr =25.1km = 25100m
r = (25100/2π)m
G = 6.67 10-11m3kg-1s-2
Substituting the values to equation 1
M = (2×1.4/29.4^2)×((25100/2π)^2)/(6.67 × 10^-11)
M = 7.75 × 10^14 kg