n principle, any time someone jumps up, the Earth moves in the opposite direction. To see why we are unaware of this motion, calculate the recoil speed of the Earth when a 75 kg person jumps upward at a speed of 2.0 m/s

Explanation:.

Given that,

Let the mass of the person be

m = 75kg

Mass of the earth is

M = 6 * 10²⁴ kg

Spend of the person is

v = 2m/s.

Let the recoil speed of the earth be V.

Using conservation of momentum

P (initial) = P (final)

Initial momentum is 0

Pi = Pf

0 = mv + MV

V = - mv/M

V = - 75 * 2 / 6*10²⁴

V = - 2.5*10^-23 m/s

Therefore, the recoil speed of the earth is 2.5*10^-23 and it is very very small, therefore, it is unmeasurable.