Projectiles have horizontal and vertical motion and follow a curved path.
e.g. A football being kicked.
Satellite Motion
Newton’s thought experiment
Newton imagined a giant cannon on top of a mountain firing cannon balls. The cannon balls are projectiles following a curved path towards the earth as shown. However, if they are fired with a high enough speed, they will “fall” into a circular orbit.
Due to gravity and the curvature of the earth, the ball will remain in orbit.
Objects in orbit appear to be weightless, but are actually in constant freefall.
Apparent Weightlessness
Astronauts in orbit around the Earth are in a constant state of free-fall. The spaceship, the astronauts and everything inside are all accelerating towards the Earth due to gravity.
This is known as apparent weightlessness. The effects are because of gravity, and not because they have escaped from the gravitational field of the Earth.
Space exploration and our understanding of the Earth
Satellites have allowed us to make observations of the Earth.
Important observations of the environment have been made using monitoring satellites in orbit around the Earth, including:
- reduction of rainforest
- melting of polar icecaps
Technologies arising from space exploration
Some examples include
- Weather forecasting
- GPS and Sat Nav
- Global communication
- Satellite TV
- Protective paints
NASA has a website called “Spin-off” which shows how technologies developed in their Space Programme have benefits in everyday life –
http://spinoff.nasa.gov/Spinoff2008/tech_benefits.html
For any technology that you provide, you must be able to describe the impact that it has on our everyday life.
Age of the universe
Current thinking dates the age of the universe as approximately 14 billion years.
