1) For object on surface not to be thrown off, gravitational
attraction must provide the necessary centripetal force.
Hence,
mrw^2= GMm/r^2
where m = arbitrary mass of an object on surface, M is mass of
planet, r = radius of planet = distance between center of planet to
object on surface, G = gravitional constant
mrw^2 = GMm/r^2
r^3 x w^2/G = M
M = 4.7 X 10^24kg
2i) W = mg where W = weight of truck = force needed to lift truck
where g = gravitational acceleration of truck on surface, peculiar
to the mass of the planet
Since gravitational force = GMm/r^2 = mg, where r = radius of
planet = distance between center of mass of planet and object on
surface of planet
g = GM/r^2 = ( 6.67 x 10^-11 x 5 x 10^15 ) / (7 x 10^3)^2 = 6.8 x
10^-3
Hence, force needed to lift truck = mg = 2000 x 6.8 x 10^-3 = 13. 6
N.
For most adults, 13.6 N is not a problem, so ans is can lift the
truck.
ii) ?
