The simplest question in physics
When you jump, gravity pulls you back down. That is obvious. But here is the question: what if you jumped really hard? Hard enough to never come back down?
It sounds like a silly question. But answering it properly leads to one of the most important concepts in physics: escape velocity — the minimum speed an object needs to break free from a planet's gravitational pull entirely.
How high can you actually jump?
An average person can jump about 0.5 meters off the ground. An elite athlete might reach 1 meter. The world record for a standing jump is roughly 1.65 meters. Your legs can push you upward at about 3.1 m/s at best.
To escape Earth, you would need to leave the surface at 11,186 m/s. That is roughly 40,000 km/h — about 33 times the speed of sound.
Here is how your jump compares:
Your jump does not even register on the scale. A bullet gets to about 10% of escape velocity. Only a rocket can reach it — and even then, it takes thousands of tonnes of fuel.
Why is escape velocity so high?
Escape velocity depends on two things: the planet's mass and its radius. More mass means stronger gravity. A smaller radius means you are closer to the center, which also means stronger gravity.
Earth is massive — 5.97 × 10²&sup4; kg — and you are standing only 6,371 km from its center. That combination creates a gravitational pull that requires enormous speed to overcome.
But here is the surprising part: escape velocity does not depend on the object's mass. A tennis ball and a space shuttle need exactly the same speed to escape Earth. The difference is that a shuttle can generate enough thrust to reach that speed.
Escape velocity is about the planet, not the object. A 1 kg rock and a 100,000 kg spacecraft both need 11,186 m/s to leave Earth. Mass determines how much fuel you need — not how fast you have to go.
What about other planets?
Escape velocity is different everywhere in the solar system. On the Moon, it is only 2,380 m/s — low enough that the Apollo missions could leave with a relatively small engine. On Jupiter, it is a staggering 59,500 m/s. No human-built vehicle could escape Jupiter from its surface.
| Body | Escape velocity | Compared to Earth |
|---|---|---|
| Moon | 2,380 m/s | 0.21× Earth |
| Mars | 5,030 m/s | 0.45× Earth |
| Earth | 11,186 m/s | 1.00× |
| Saturn | 35,500 m/s | 3.17× Earth |
| Jupiter | 59,500 m/s | 5.32× Earth |
| Sun | 617,700 m/s | 55.2× Earth |
Notice the pattern: more mass and smaller radius means higher escape velocity. This is exactly what Newton's gravitational law predicts — the same formula you learn in the first Physiworld gravity lesson.
The Escape Velocity Simulator on Physiworld lets you select different celestial bodies, change altitude, and see how escape velocity changes in real time.
What does this have to do with GPS?
GPS satellites orbit Earth at about 20,200 km above the surface. At that altitude, gravity is weaker — and escape velocity is lower. But the satellites are not trying to escape. They are in orbit, constantly falling around Earth, the same way the ISS does.
Here is the connection: because gravity is weaker at GPS altitude, time itself passes slightly faster for the satellites than it does on the ground. This is a real, measurable effect. GPS systems have to correct for it — if they did not, your location would drift by about 10 km per day.
So escape velocity, gravitational fields, and even the accuracy of your phone's map are all connected by the same physics.
Try it yourself
The Physiworld gravity lesson includes an Escape Velocity Simulator where you can select Earth, the Moon, or Jupiter, set an altitude, and see the calculated escape velocity. It also includes a gravitational field game where you control an object falling through space.
So, can you jump off a planet?
Not Earth. Not even close. But there are places in the solar system where it might be possible. On some small asteroids, escape velocity is less than 1 m/s — slow enough that a gentle jump would send you drifting off into space, never to return.
On the asteroid Bennu, for example, escape velocity is about 0.2 m/s. A casual step would launch you into orbit. A proper jump would send you away forever.
That is the same formula, the same physics, just applied to a much smaller mass. Everything you have learned in this gravity section — from why astronauts float to why the Moon stays in orbit to what happens if gravity disappears — all comes down to mass, distance, and the equations that connect them.
Escape velocity is the minimum speed needed to leave a planet's gravitational pull. On Earth, it is 11,186 m/s — far beyond any human jump. It depends only on the planet's mass and radius, not the object's mass. The same physics explains why GPS clocks run differently in orbit and why you could jump off a small asteroid but never off Earth.
Calculate escape velocity for different planets, answer practice problems on gravitational fields, and play the gravity falling game to finish the section and unlock the Gravity Quiz.
The Gravity section covers Newton's Law, weight calculations, free fall, escape velocity, and gravitational fields across 5 interactive lessons.