Gunpowder was discovered long before WWII. It was used to propel bamboo rockets in China. The requirements of WWII called for heavy payloads and the use of more powerful fuels such as kerosine and liquid oxygen. Wernher von Braun's V2 rocket was a brilliant design which gave birth to modern day space travel. Militarily it was of little consequence. The V2 rockets that landed on London in 1944 were terrifying but little else.

The V2 rockets are bound by Sir Isaac Newton's Third Law of Motion that states that "For every action there is an equal and opposite reaction.". The expulsion of gases, resulting from the combustion of fuel, through the exhaust nozzle produces a reactive force on the rocket in the opposite direction causing the rocket to be propelled upwards.

Since force is the product of mass and acceleration (F=ma, where m=mass, a=acceleration) then the greater the mass of the gas escaping the nozzle and the greater the acceleration of this gas the greater the force that propels the rocket.

So it is important to burn a great deal of fuel quickly to generate significant mass of escaping gas and it must burn as hot as possible to generate a high velocity of gas particles escaping the nozzle. The V2 burnt 143 litres of fuel every second to create exhaust gases that escaped at 2,700 C.

The rocket has to overcome the constant force of gravity which is pushing it down towards the ground. It must produce a greater force upwards, known as thrust, in order to accelerate skyward. Air resistance is another force that acts to stop the rocket from moving skyward. Air resistance is sometimes called drag and increases with speed. The faster a rocket travels through the air the harder it will slam into air molecules that will resist its movement through them.

The force of thrust is produced by air resistance produced by escaping exhaust gases

Gravity is the force generated by the collision with air particles the earth exerts on the rocket and weakens the further away from earth the rocket is. that pushes the rocket skyward

The rocket accelerates skyward because thrust overcomes the force of gravity only the forces of gravity and air resistance the force of air resistance only

Air resistance is often called drag. Drag increases as the speed of the rocket decreases decreases as the rocket speeds up increases as the rocket speeds up. stays constant no matter what he speed of the rocket is.

Gravity is a force that increases as the speed of the rocket decreases decreases as the rocket speeds up increases as the rocket speeds up. stays constant no matter what he speed of the rocket is.

Thrust is the force that increases as the speed of the rocket decreases decreases as the rocket speeds up increases as the rocket speeds up. stays constant no matter what he speed of the rocket is.

Thrust is the force that can be adjusted by altering the rate fuel burns. increases as the rocket slows down stays constant no matter what he speed of the rocket is.

The formula F= ma tells us that the force produced by a rocket is has nothing to do with the speed of the escaping exhaust gases. tells us that the force produced by a rocket is has nothing to do with the mass of the escaping exhaust gases. tells us that the force produced by the rocket increases as the amount of fuel per second increases.

In the formula F= ma temperature of the escaping gases has no effect on the force. no effect on the mass of gas. the effect of increasing the acceleration of the gas escaping. no effect on acceleration of the escaping gases

Thrust to propel the V2 rocket is generated when the exhaust gases push against the launch pad the exhaust gases push against air molecules exhaust gases stream out of the exhaust nozzle

Out in space where there is no air a space craft can not propel itself forward can not move at all must carry its own oxygen supply to burn its fuel