Newton’s second law of motion is essentially a mathematical equation, stating that force is equal to mass times acceleration or f=ma. When a rocket is launched, thrust continues for as long as the engines are firing. This is because the mass of the rocket changes during flight. The largest parts of the rocket’s mass are the propellants, an amount that constantly changes, causing the mass to decrease during flight. In order for both sides of the equation to remain balanced however, the acceleration must increase, accounting for why a rocket accelerates as it moves into space. Put simply, this second law of motion can be stated in relation to the physics of rockets, ‘the greater the mass of rocket fuel burned and the faster the gas produced can escape the engine, the greater the thrust of the rocket.
Newton’s third law of motion states that for every action there is an equal and opposite reaction. When a rocket launches, the action is the expelling of gas out of the engine. The reaction is the movement of the rocket in the opposite direction. To enable a rocket to lift off, the thrust (action) must be greater than the mass of the rocket. This is different in space however, where even minute thrusts will cause the rocket to change motion. Moving through the air causes drag, impeding the motion of the rocket. As a result rockets are able to work much better in space where there is no air. These points needed to be taken into consideration when planning the Apollo project.
Gravity and weight are important considerations in space travel. Scientist has found that it was advantageous to launch rockets closer to the equator as the Earth rotates at a greater speed at the equator than at the poles. This is because the Earth is oblate (wider around the middle as it is not a perfect sphere). Additionally, launching the spacecraft at the equator provides an additional 1,667km/h once it reaches orbit. The extra speed means that less fuel is needed. As a result the freed space can be used to carry more payload. During flight, the weight of a rocket is constantly changing as the vehicle burns up fuel. Engineers have hence established several mass ratios which help the performance of a rocket with changing mass. For example, full scale rockets are often broken into smaller rockets which are discarded during flight to increase performance.
Spacecrafts store and use many different types of energy. They also undergo many different energy transformations throughout the duration of their journey. Rocket boosters contain energy stored in the form of chemical potential energy. The external tank contains gases which are used by the engines of the shuttle and also contain chemical potential energy. Electrical devices on the space shuttle such as computer require electricity, meaning that somewhere on the shuttle, a form of electrical energy must be present.
During the flight, the spacecraft undergoes many energy transformations. One of these is the chemical potential energy of the rocket boosters and external tank being transformed into kinetic energy and gravitational potential energy. When the shuttle re-enters Earth, it must go through another energy transformation, converting friction into thermal energy. The left over kinetic energy is transformed into thermal energy upon touch down due to friction between the wheels and the runway. Before touchdown, however, some of the kinetic energy is transformed into sound energy (sonic boom) as the spacecraft slows down from its previous supersonic speed. In summary, during a space shuttle’s journey:
Chemical potential energy is transformed into kinetic energy and gravitational potential energy, which is then transformed into thermal and sound energy. These factors were important in designing the Apollo space mission.
Using the physics of roller coasters have assisted engineers and scientists in perfecting space travel. Concepts of roller coasters such as free fall and acceleration are all experienced during space travel. Feelings of low and high-gravity on rollercoasters have been designed to imitate turbulence, acceleration and free falls on air and spacecrafts. Modern technology has enabled the recreation of various gravitational conditions of space travel and vertical loops of a rollercoaster. Using these concepts, low-gravity research aircraft which fly in parabolic shaped paths have become available, enabling researchers to investigate the effect of microgravity on astronauts and conduct experiments to further increase knowledge on space travel.
It can therefore be concluded that the Apollo program which landed the first man on the moon was truly a great feat. Many complicated calculations and principles of physics needed to be accounted for in order to ensure its success, with information taken from various sources. Consequently, the Apollo program was also one of the most costly and intricate tasks of the time, made achievable by immense motivation.
