Physics - NLM Question with Solution | TestHub

You are able to spring up because the earth exerts a force upward on you which is stronger than downward force you exert on the earth.

Since the ground is stationary, it cannot exert the upward force necessary to propel you into the air.

When you push down on the earth with a force greater than you weight, the earth will push back with the same magnitude force and thus propel you into the air.

When you jump up the earth exerts a force ${\mathrm{F}}_1$ on you and you exert a force ${\mathrm{F}}_2$ on the earth. You go up because ${\mathrm{F}}_1>{\mathrm{F}}_2$, and this is so because ratio of ${\mathrm{F}}_1$ to ${\mathrm{F}}_2$ is earth's mass ratio to your mass.