It is given that the mass of Earth is 6 x 10²4 kg and the radius of Earth is 6400 km. Calculate the value of acceleration due to gravity on the surface of Earth. Given g = 6.7 x 10⁻11 Nm²/kg².
a) 9.8 m/s²
b) 8.9 m/s²
c) 10.2 m/s²
d) 7.6 m/s²