Exercise \(\PageIndex{1}\): Determine the unknown mass
A \(100\text{-kg}\) mass can be moved around (by click-dragging it) near an unknown mass as shown in the four animations (distance is given in meters and force is given in newtons). The table shows how the force on the unknown mass changes due to the position of the \(100\text{-kg}\) mass. Restart.
- Which animation is physical? Why?
- For that animation, what is the mass of the unknown mass?
Exercise \(\PageIndex{2}\): Determine the mass of the star
A planet orbits a star (yellow) as shown in the animation (position is given in \(R_{\text{Earth Sun}}\) and time is given in Earth days). Determine the mass of the star. Restart.
Exercise \(\PageIndex{3}\): Determine the mass of the orbiting planets
Two planets orbit a star (red), whose mass is \(M = 7\times 10^{25}\text{ kg}\) as shown in the animation (position is given in \(10^{6}\text{ km}\) and time is given in Earth years). Restart.
- What is the net force on the central star? Write an expression, not a numerical answer.
- What is the net force on each planet? Write an expression, not a numerical answer.
- Determine the mass of the orbiting planets.
Exercise \(\PageIndex{4}\): Determine the mass of the star
A planet has an initial velocity in the y direction that gives it a slightly elliptical orbit around a star as shown in the animation (position is given in \(10^{6}\text{ km}\) and time is given in years). Restart.
- Determine the mass of the star.
- What is the correct orbital radius to give circular motion? Drag the planet at \(t = 0\) to determine this radius. You may also drag the gray blocks around to use them as temporary or permanent markers.
Exercise \(\PageIndex{5}\): Could this animation of a planetary orbit depict a physical situation?
The animation purports to model a solar system. However, the planet shown is not in a circular or an elliptical orbit (position is given in \(10^{4}\text{ km}\) and time is given in years). Restart.
- Could this represent a physical situation?
- Why or why not?
When you get a good-looking graph, right-click on it to clone the graph and resize it for a better view.
Exercise \(\PageIndex{6}\): Kepler's laws
The animation purports to model a solar system. However, one of the planets does not obey all of Kepler's laws for this solar system (position is given in \(10^{6}\text{ km}\) and time is given in Earth years). Identify that planet. (The sun is yellow.) Restart.
Exercise \(\PageIndex{7}\): Determine the speed for circular orbit
A satellite orbits a planet as shown in the animation (position is given in \(10^{3}\text{ km}\) and time is given in Earth days). If the satellite's orbit above the planet were doubled, what would its speed have to be in order for it to stay in a circular orbit? Restart.
Exercise \(\PageIndex{8}\): Determine the mass of the star
The animation shows a comet orbiting a star (position is given in \(10^{6}\text{ km}\) and time is given in Earth years). Determine the mass of the star. Restart.
Exercise \(\PageIndex{9}\): Determine the acceleration
A rocket accelerates upward while a ball is fired into the opening in the rocket as shown in the animation (position is given in meters and time is given in seconds). The rocket and the ball are far from any massive object. For an observer in the rocket, what acceleration does the ball appear to have? Restart.
Exercise \(\PageIndex{10}\): Tunnel through the earth
A very wealthy individual proposes to dig a hole through the center of Earth and run a train (the small black circle) from one side of Earth to the other as shown in the animation (position is given in Earth radii and time is given in seconds). Which of the animations correctly depicts the motion of the train? Ignore frictional effects and treat Earth as a uniform mass distribution. Restart.
Physlets were developed at Davidson College and converted from Java to JavaScript using the SwingJS system developed at St. Olaf College.
