5.6.7 Circular Motion

Understanding Circular Motion

Centripetal Force

Orbits of Satellites

There are two main types of satellite orbits:

1. Polar Orbits:

• Satellites in polar orbits pass over the Earth's poles.
• These satellites travel very close to the Earth, often as low as 200 km above sea level.
• Due to their proximity to the Earth, they must travel at high speeds, nearly 8,000 m/s, to maintain their orbit.
• Polar orbits are typically used for Earth observation, weather monitoring, and reconnaissance.

2. Geostationary Orbits:

• Satellites in geostationary orbits take 24 hours to complete one orbit around the Earth.
• These satellites are positioned much higher than those in polar orbits, at around 36,000 km above the Earth's surface.
• Because of their altitude, they move more slowly, at about 2,000 m/s.
• From the ground, a geostationary satellite appears to stay in the same spot in the sky, making them ideal for communications, television broadcasting, and weather forecasting.

Summary

In circular motion, even if an object moves at a constant speed, it is still accelerating due to the continuous change in direction. This acceleration is caused by a centripetal force, which pulls the object toward the centre of the circle. Examples include tension in a string, friction between tyres and the road, and gravitational pull in satellite orbits. Understanding the role of centripetal force is key to understanding how objects maintain their circular paths, whether it's a simple conker on a string or a sophisticated satellite orbiting Earth.