Given,
Momentum of earth, =MV
Momentum of stone, =mv
From conservation of momentum
Initial momentum = final momentum
0=MV+mv
V=−mvM=−5×366×1024=3×10−23 m/s
Recoil velocity of earth is 3×10−23m/s
What is the force of gravity on a body of mass 150 kg lying on the surface of the earth? (Mass of earth =6×1024 kg; Radius of earth = 6.4×106m;G=6.7×10−11Nm2/kg2)