Newton’s Second Law
Newton’s second law states that an object’s acceleration is proportional to the force applied to it. In equation form, the force "F", the object’s mass "m", and the acceleration "a", then Newton's Second Law is simply "F=ma".
This is how the rocket lifts off. An unbalanced force must be exerted for the rocket to lift off the launch pad.
Newton’s Third Law
The amount of thrust, force produced by the engine, will be determined by the mass of rocket fuel that is burned and how fast the gas escapes the rocket.
Newton's Third Law states that for every action there is an equal and opposite reaction. This is how the rocket ascends. The thrust creates an opposite reaction which pushes the vehicle upwards. The higher the velocity or mass of the gas, the greater the thrust.
Gravity and Weight
According to Newton’s Law of Universal Gravitation, the larger a body's mass and the closer to a body an object is, the stronger the force of gravity on that object. The spacecraft has to travel at a larger force than that of gravity on Earth to escape the pull of the Earth’s gravity. This requires a lot of energy.
Mass refers to the amount of matter an object contains and weight refers to the force with which the gravity of a planet pulls on an object. On the moon, gravity is only 1/6 of that of Earth’s, meaning it is easier to move around.
In orbit, all things are in free fall. Earth's gravity is still pulling, but free fall simulates the effect of no gravity. Thus, Astronauts face weightlessness in space, this can result in serious long-term health problems, because they are in a constant state of free fall. However, they still have mass. This means they must push on something in order to move about the shuttle, and rely more upon their arms to move about.
Energy Considerations and Transformations
For energy considerations of rockets, it is often important that as much of the energy stored in the propellant ends up as kinetic energy of the body of the rocket as possible, with as little as possible wasted in the exhaust jet as a lot of energy is lost in the kinetic energy of the exhaust gases.
Before rocket boosters start up, they are filled with chemical potential energy. This energy chemical potential energy is transformed into kinetic energy and gravitational potential energy when the engines start up. This energy stays as kinetic energy and gravitational potential energy when the space shuttle is in orbit and when it is coming back to Earth.
When the space shuttle re-enters the Earth’s atmosphere the energy in transformed into thermal energy though friction and more friction is caused when the ties of the shuttle hit the runway. The final part of energy is converted into sound energy in the form of a sonic boom, this happens when the shuttle goes from supersonic to subsonic speeds.
Space Travel and Roller Coaster Physics
The physics of roller coasters and space shuttles are quite similar. Both on roller coasters and space shuttles, a drastic change in speed is experienced. The energy conversions that take place on a rollercoaster are similar to those that take place in a space shuttle. The potential energy is first converted into kinetic energy and then the reverse will also take place.
The two objects both follow Newton’s Three Laws and take into consideration of gravity and weight.
Conclusion
Travelling into space was considered difficult because of gravity, a large amount of energy is needed to get even a small object into space, and re-entering the atmosphere seemed impossible. Supporting human life in a different environment also posed formidable issues.
Bibliography
http://www.aiaa.org/kidsplace/kidsplacepdfs/Pop%20Rockets%20Activity.pdf
http://www.astrosociety.org/education/publications/tnl/34/34.html
http://dictionary.sensagent.com/rocket/en-en/
http://en.wikipedia.org/wiki/Weightlessness
http://mathforum.org/library/drmath/view/56250.html
http://www.cartoonstock.com/directory/i/isaac_newton.asp
