A 70kg person jumps straight upward by pushing downward on Earth with an average force of 800N for 0.30s. Assuming Earth’s mass is 6.0×1024kg, which of the following is the BEST estimate of Earth’s change in speed as a result of the jump?
a) 6×10−24m/s
b) 1.3×10−22m/s
c) 4×10−23m/s
d) 4×10−21m/s