Escape Velocity

Part of the Mechanics section of Coddy's Physics journey. Lesson 89 of 94.

The escape velocity is the smallest launch speed that never comes back. The object escapes when K + U is zero or more:

v_esc = √(2GM/R) = √(2gR)

The object's own mass cancels. At the same distance, escape speed is √2 ≈ 1.41 times the orbit speed. Earth: 11.2 km/s.

A planet with a dashed circular orbit around it and an open curve leaving from the same point: at the orbit speed v the object circles, at the escape speed, about 1.41 times larger, it moves away and never returns

Same starting point: orbit speed circles, escape speed never comes back.

Challenge

A dwarf planet has a radius of 500 000 m and a surface gravity of 0.25 m/s². Find its escape velocity v_esc.

Try it yourself

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Mechanics

1Vectors and Newton's Laws

Right Triangles What is a Vector?Adding Vectors Axes and Directions Vector Components Forces Around Us Friction and Tension Newton's First Law Newton's Second Law Newton's Third Law Recap - Net Force

4Kinematics in 1D

Position and Displacement Velocity Acceleration Motion Graphs Equations of Motion Recap - Braking Car

7Kinematics and Newton

From Forces to Motion From Motion to Forces Two-Stage Motion Recap - Elevator

10Springs

Hooke's Law Springs in Series Springs in Parallel Recap - Spring Scale

13Momentum in 2D

Momentum as a Vector 2D Collisions Explosions Recap - Billiards

16Gravitation

Law of Gravitation Gravity and Altitude Satellites Kepler's Laws Gravitational EnergyEscape VelocitySatellite Energy Recap - Mission to Orbit

2Friction

What is Friction?Static Friction Kinetic Friction Friction and Newton's Laws Recap - Sliding Crate

5Vertical Motion

Free Fall Throwing Upward Time in the Air Recap - Dropped Ball

8Project: Delivery Drone

Mission Briefing Takeoff Thrust Climb to Altitude Cruise and Brake Package Drop

11Elastic Energy

Elastic Potential Energy Spring Launchers Energy with Springs Recap - Spring Launcher

14Circular Motion

Uniform Circular Motion Centripetal Acceleration Horizontal Circles Vertical Circles Loop the Loop Recap - Car on a Curve

17Final Challenges

Recap - Stunt Ramp Recap - Crash Test Recap - Space Probe

3Inclined Planes

Forces on an Incline Gravity Components Frictionless Incline Incline with Friction Will It Slide?Recap - Ramp Challenge

6Projectile Motion

Independent Axes Horizontal Launch Launch at an Angle Range and Max Height Recap - Hit the Target

9Work and Energy

Work Kinetic Energy Work-Energy Theorem Gravitational PE Conservation of Energy Power Recap - Roller Coaster

12Impulse and Momentum

Momentum Impulse Conservation of Momentum Elastic Collisions Inelastic Collisions Recap - Air Track

15Simple Harmonic Motion

What is SHM?Mass on a Spring The Pendulum SHM Graphs Energy in SHM Recap - Oscillator