Why do rockets have to go so fast to reach orbit?

Orbit is not just high altitude; it is also high speed. To stay in low Earth orbit, a spacecraft must travel roughly 7.8 kilometers per second, or about 28,000 kilometers per hour, though the exact value depends on altitude and mission profile. Rockets must accelerate gradually because they are fighting gravity and atmospheric drag while carrying fuel, payload, and structure. The large speed requirement is why orbital launch is much harder than a suborbital hop.