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Concordian International School

IBDP Physics (2025): D.1 Gravitational fields (+HL)

This guide is for the DP Physics syllabus with first assessments in 2025

D.1 Gravitational fields (+HL)

Demos and simulations

Part 1

  1. Choose "First Law"
  2. Press Play (triangle) and observe the planet orbiting the star
  3. Grab the purple planet and drag it so that the orbit changes. What shape is the orbit always?

 

 

 

Part 2

  1. Choose "Second Law"
  2. Press Play (triangle) and observe the planet orbiting the star.
  3. What can you say about the area swept by the planet in the same time interval?
  4. What can you say about the speed of the planet when it's close to the star compared to when it's far away? Why?

 

 

Part 3

  1. Choose "Third Law"
  2. Press Play (triangle) and observe the planet orbiting the star.
  3. Drag the yellow slider on the left and observe the graph. This changes the mass of the star.
  4. This graph is not linear, but can be linearized. How should you choose the axes so that you'll get a linear graph?
  5. Use this linear graph to express a proportional relationship.

 

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  1. Only change the initial projectile speed.
  2. Click Fire

What is the smallest speed you can fire the rocket so that it doesn't return to the Earth? This is the escape velocity. 

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                                                   v = 4 km/s                                          v = 6km/                                v = 8km/s (circular orbit)                8km/s < v < 11 km/s (elliptical orbit) 

Extra information (not part of syllabus)

Speed Orbit State
less than 8 km/s c                              Crashes                                 Bound                                           
8 km/s Circle Bound
8 km/s - 11.2 km/s Ellipse Bound
11.2 km/s Parabola Free
more than 11.2 km/s Hyperbola Free

 

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  1. Click + to add the initial speed of the satellite. Observe what happens to the total mechanical energy of the satellite.
  2. Click the play button to launch the satellite.

What kind of trajectory do you get when the total mechanical energy is negative?

What kind of trajectory do you get when the total mechanical energy is positive?

NOTE! You need to reload the page in order to restart the simulation!

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  1. Move the masses around and observe what happens to the total potential.
  2. Change the mass and observe what happens to the total potential?

Where is the gravitational potential zero?

Where is the gravitational field zero?

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My apologies - the controls do not work when embedded. Please find the simulation here

Note that you can click "delete" to remove a mass.

Gravitational field strength is decreasing with increasing distance between the equipotential lines

  

Simulation here. (Go to: Physlets in the second semester --> connecting potential to force)