Gravitation

Physics · Class 11

Simulation · Physics · Class 11

Climbing out of a gravity well

"Climbing out of a gravity well" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the NCERT section "Escape speed" in Gravitation. Fire a ball straight up from a planet; the −GMm/r potential well and the total-energy line show how high it rises and when it escapes. NEET has asked about this idea 4 times in 10 years of papers. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).

From the lesson Escape speed in Gravitation. Change the values and watch what happens.

Climbing out of a gravity wellPhysics · Class 11

What it shows

NCERT §7.8

Fire a ball straight up from a planet; the −GMm/r potential well and the total-energy line show how high it rises and when it escapes.

Controls

3 to try

  • Sliderlaunch speed as fraction of escape speed 0–1.2
  • Sliderplanet radius 0.5–3 R_E
  • Sliderplanet density 0.5–2 ρ_E

Try this

Launch at half the escape speed and find the maximum height (R/3); then find the planet radius at which escape speed doubles at fixed density.

Common mistake

Using h = u²/2g for large heights; heavier bodies need more escape speed.

In NEET

10 years of papers

Asked 4 times in 10 years of NEET.

See the past questions: Gravitation, Gravitation (chapter)

In JEE Main

42 shifts analysed

39 questions from Gravitation across the 42 JEE Main shifts Lumi has analysed (2017–2026).

See the past questions

The idea behind it

NCERT §7.8

  • Escape speed is the least launch speed that lets a body reach infinity and never return, with air resistance ignored.
  • Energy conservation: ½ m vᵢ² − G M_E m / (R_E + h) must be at least zero, the least total energy a body can have at infinity.
  • From the surface (h = 0): vₑ = √(2 G M_E / R_E) = √(2 g R_E) ≈ 11.2 km/s.
  • Escape speed does not depend on the mass of the body or the direction of launch; it does depend on the planet and on the launch height.
  • For the Moon, with its smaller g and radius, the escape speed is about 2.3 km/s, about five times smaller. Gas molecules moving faster than that leave for good, which is why the Moon has no atmosphere.
  • Between two spheres of masses M and 4M, radius R, centres 6R apart, the pulls cancel at 2R from the smaller one. A body fired from M only needs to reach that neutral point: v_min = (3GM/5R)^½.

Questions

5 answers

What does the "Climbing out of a gravity well" simulation show?
Fire a ball straight up from a planet; the −GMm/r potential well and the total-energy line show how high it rises and when it escapes.
What mistake does the "Climbing out of a gravity well" simulation fix?
A common mistake it clears up: using h = u²/2g for large heights; heavier bodies need more escape speed.
Has NEET asked about this idea?
Yes. NEET has asked about this idea 4 times in 10 years of papers.
Does JEE Main ask questions from Gravitation?
Yes. JEE Main asked 39 questions from this chapter across the 42 shifts Lumi has analysed (2017–2026).
Is this simulation free?
Yes. It is free and runs in the browser on a phone or a laptop. It belongs to the lesson "Escape speed" in Gravitation (Class 11 Physics).

Embed this simulation

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