**Learn how to understand launch velocity and its impact on satellite orbits through a satellite launch model into orbit.**

**SCIENCE** – Natural satellites are celestial bodies that orbit other celestial objects, such as the Moon orbiting the Earth. Artificial satellites are human-made objects that orbit the Earth. Artificial satellites are placed at desired altitudes above Earth and launched by rockets parallel to Earth’s surface. Forward velocity and gravitational force cause satellites to remain in orbit around Earth. In this experiment, you will study launch velocity and its effects on the orbit of human-made satellites. You will determine optimal times to observe satellites and measure their angular velocity. You will also understand why satellites are launched in various directions.

**Learning Objective**

Creating a model of how a satellite is launched into orbit. Materials 2 identical-sized books, each approximately 25 cm long Index cards Transparent tape 3 rulers – 2 rulers should be identical and have markings at the center Playdough, fist-sized amount Bath towel Marble

**Procedure**

- Align the two books end to end on a table.
- Place an index card on top of the book ends, extending beyond the table edge.
- Attach the grooved ends of the rulers together, with one end meeting the other. Tape only on the non-grooved side. This is your launcher.
- Position the launcher on the books so that one end is above the index card. Raise that end 5 cm above the book. Place playdough under that end as a support. Let the other end of the launcher extend beyond the book.
- Adjust the book’s position so that the extended end of the launcher is 10 cm from the table edge.
- Place a towel on the floor near the table edge. The towel will catch the marble when it falls to the ground.
- Position the marble on the raised end of the launcher, then release the marble (see below). The marble should fall onto the towel.
- Observe the marble’s path after it leaves the launcher.

**Results**

The marble’s path forms an arc after leaving the launcher.

**Why?**

In this model, the table represents Earth. The top of the book is where the “marble satellite” is launched horizontally, parallel to Earth’s surface. After separating from the launcher, the satellite moves in a curved path. This curve arises from the satellite’s forward horizontal velocity (representing a specific direction) and the downward gravitational pull. A real satellite would continue along the curved path and return to its launch point.

**Try a New Approach**

If the horizontal velocity of the marble satellite is sufficiently high, Earth’s gravity pulls it into a curved path beyond the table’s edge. Explore the effect of different horizontal velocities on the satellite’s path by repeating the experiment, raising the launcher to various heights.

**Design Your Own Experiment**

a. Earth’s surface curves away from a tangent line (touching at one point) to its surface at a rate of 3 -JQ miles (4.9 km) per every 5 miles (8 km). Thus, near Earth’s surface, an object flying at a speed of 5 miles (8 km) per second will maintain its altitude and move in a curved path around Earth. Create a diagram illustrating the effects of launch velocities greater, smaller, and equal to 5 miles (8 km) per second.

b. Satellite horizontal velocity depends on its altitude above Earth, affecting the gravitational force acting on the satellite. Gravitational force at a specific distance from Earth’s center can be calculated using the following equation: g1 / g2 = r22 / r12 g1 = 9.8 m/s², gravitational acceleration at Earth’s radius (at the surface) r1 = 12,757 km, Earth’s radius g2 = gravitational acceleration at distance r2 r2 = distance from Earth’s center to satellite orbit For sample data, random error will be: E = 2° : √(5 – I) = 2° : √4 = 2° : 2 = 1° To express the random error of your measurement, you would state that the angle value is 29.6° ± 1°. This means the measurement lies between 28.6° and 30.6°.”