Mass and radius of earth are 6*10^24kg. and 6.4*10^6 m. Calculate the following?

1.Work done in carrying a body of mass 10 kg. from earth's surface to infinity.
2.Gravitational potential energy of the body on earth's surface.
3.The velocity of the body,when it falls on the surface of earth from infinity.

#1.
G = 6.67384 × 10^(-11) m^3 kg^(-1) s^(-2)
W = GmM/R = 6.67384 × 10^(-11) × 10 × 6 × 10^(24) / 6.4 × 10^6 = 6.3 × 10^8 J.

#2.
V = GmM/R = 6.67384 × 10^(-11) × 10 × 6 × 10^(24) / 6.4 × 10^6 = 6.3 × 10^8 J.

#3.
(1/2)mv^2 = GmM/R
v^2 = 2GM/R
v^2 = 2 × 6.67384 × 10^(-11) × 6 × 10^(24) / 6.4 × 10^6 = 1.3 × 10^8
v = 3.5 × 10^4 m/sec