Any projectile launched from Earth is slowed by interaction with the atmosphere. Most of this interaction is caused by friction. If we can talk about launching without worrying about the drag caused by friction, the discussion is easier. We can use the idea of conservation of energy to discover the velocity needed to escape the Earth's gravitational pull. If the energy of motion (kinetic energy) of a projectile just equals the pull of gravitational (potential) energy, the projectile can barely escape the Earth.
Notice that the mass of
the projectile can cancel on both sides of the equation. This is why
the escape velocity is
Both a pebble and a rocket must each obtain an escape velocity of 11.2 km/s to escape the Earth. Obviously it would require
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