Physics · Class 11

Resize a satellite orbit

Gravity supplies centripetal acceleration in a circular orbit. Higher orbits have lower speed but greater circumference, so the period grows. Their total orbital energy is less negative.

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Resize a satellite orbit

வட்டச் சுற்றுப்பாதையில் ஈர்ப்பு விசை மையநோக்கு விசையாகும். உயரம் அதிகரித்தால் வேகம் குறைந்து சுற்றுக்காலம் அதிகரிக்கும்.

Key notes, relationships and model limits

Key relationship

v=√(GM/r); T=2π√(r³/GM); E=−GMm/(2r).

Remember

Gravity supplies centripetal acceleration in a circular orbit. Higher orbits have lower speed but greater circumference, so the period grows. Their total orbital energy is less negative.

Common trap

Satellite weight is not zero in orbit; gravity continuously bends the trajectory.

Model limits

Circular exterior orbit about spherical Earth; no atmosphere, thrust or perturbations. Altitude is added to Earth radius.

What you will learn

Relate orbital radius, speed, period and total energy.

Try the experiment

Try both scenarios, change one control, and predict the result before checking the graph and readouts.

Think of it this way

Change one input while keeping the others fixed, as you would in a controlled experiment.

Worked example

At 400 km altitude, r=6.771×10⁶ m, v≈7.673 km/s and T≈5545 s, about 92.4 minutes.

Why this matters

The model connects resize a satellite orbit with an observable reading. Check the equation and assumptions before applying it.

Before you start

SI units · algebra · graph reading

Check your understanding

If orbital radius doubles, how does period change?

It doubles
It multiplies by 2√2
It multiplies by four

Read the explanation

T is proportional to r^(3/2), so T(2r)/T(r)=2^(3/2).

Course connection: Class XI Chapter 7. Consult the roadmap for CBSE, NEET, JEE Main and Advanced scope.