Satellite dashboard
"Satellite dashboard" is a free, interactive Class 11 Physics simulation for NEET and JEE, built on the NCERT section "Earth satellites" in Gravitation. Drag a satellite's orbit radius: v, T, K, U and E update with T² ∝ r³ on a log plot and E = −K. 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 Earth satellites in Gravitation. Change the values and watch what happens.
What it shows
NCERT §7.9, §7.10
Drag a satellite's orbit radius: v, T, K, U and E update with T² ∝ r³ on a log plot and E = −K.
Controls
3 to try
- Drag/sliderorbit radius 1–10 R_E
- Toggleplot T vs r / T² vs r³
- Toggleenergy bars K, U, E
Try this
Find the orbit radius with a 24 h period (≈6.6 R_E) and read the energy needed to raise a 400 kg satellite from 2 R_E to 4 R_E.
Common mistake
Higher orbits are faster; a satellite's total energy is positive.
In NEET
10 years of papers
Asked 4 times in 10 years of NEET.
See the past questions: Uniform Circular Motion, Gravitation, Gravitation (chapter)
In JEE Main
42 shifts analysed
39 questions from Gravitation across the 42 JEE Main shifts Lumi has analysed (2017–2026).
The idea behind it
NCERT §7.9
- A satellite is a body that revolves around the earth; Kepler's laws apply to it just as to planets around the sun. The Moon is the earth's only natural satellite, with a period of about 27.3 days.
- For a circular orbit of radius R_E + h, gravity supplies the centripetal force: m v²/(R_E + h) = G M_E m / (R_E + h)², so v = √(G M_E / (R_E + h)), less for higher orbits.
- Just above the surface (h ≈ 0) the orbital speed is v = √(g R_E) ≈ 7.9 km/s, and the escape speed is √2 times this.
- Period: T = 2π (R_E + h)^(3/2) / √(G M_E), so T² = k (R_E + h)³ with k = 4π²/(G M_E). This is Kepler's third law for satellites.
- For an orbit just above the surface, T₀ = 2π √(R_E/g) ≈ 85 minutes.
- The same law weighs other planets. Phobos circles Mars in 7 h 39 min at 9.4 × 10³ km, which gives a Mars mass of about 6.48 × 10²³ kg; with its orbit 1.52 times the earth's, a Martian year is (1.52)^(3/2) × 365 ≈ 684 days.
- An astronaut in orbit feels weightless not because gravity is small there, but because the astronaut and the craft are falling freely towards the earth together.
Questions
5 answers
- What does the "Satellite dashboard" simulation show?
- Drag a satellite's orbit radius: v, T, K, U and E update with T² ∝ r³ on a log plot and E = −K.
- What mistake does the "Satellite dashboard" simulation fix?
- A common mistake it clears up: higher orbits are faster; a satellite's total energy is positive.
- 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 "Earth satellites" in Gravitation (Class 11 Physics).
Embed this simulation
Free, with a link back
Teaching this idea? Put the simulation on your own page or LMS with this code.