Class 11 Physics simulations · Gravitation

Falling through a tunnel in the Earth

Drop a ball into a straight frictionless tunnel through a uniform planet. It oscillates in SHM.

Open the simulation

What to notice

Every straight tunnel — through the centre or not — gives the same period, about 84 minutes for Earth.

Key relation

T = 2π √(R/g) = 2π √(3 / 4πGρ)

Try this

Move the tunnel away from the centre. Does the period change? Does the top speed?

What you can change

• Tunnel offset from centre: 0 to 0.9 × R
• Planet density: 0.3 to 2 × Earth

More in Gravitation

• Escape from a planet
• Geostationary orbit
• Satellite orbit
• Gravity above and below Earth
• Kepler’s elliptical orbit
• Energy of a circular orbit

See all Class 11 Physics simulations or every Physica simulation.