2. Escape velocity is the velocity required to just escape the gravitational pull of the planet. It depends on the ratio of the mass and radius of the planet. The formula shows that the larger the mass/radius ratio of the planet, the greater the escape velocity is. i.e. if 2 planets had the same radius, the planet with the larger mass would have a greater escape velocity. Outline Newton‘s concept of escape velocity (Jacaranda p.27) Explain the concept of escape velocity in terms of the: – gravitational constant – mass and radius of the planet Outline Newton‘s concept of escape velocity

4. The Earth’s orbital speed around the sun provides an initial velocity in space when heading to another part of the solar system. The time of the year for launch is chosen depending on which direction the Earth is heading and where you want to go. Discuss the effect of the Earth‘s orbital motion and its rotational motion on the launch of a rocket

5. ‘g forces’ refers to the ratio of apparent weight during launch to normal true weight. It is a convenient indicator of the forces on astronauts body. Jacaranda Figure 2.17 CAUTION: a ‘6g’ launch may also refer to an acceleration of a = (6 x 9.8), giving an apparent weight of 7g ! (and a g-force of 7) Identify why the term ‘g forces’ is used to explain the forces acting on an astronaut during launch A rocket accelerating upwards at 9.8 m/s 2 causes the astronaut to experience a g-force of 2. A rocket accelerating upwards at 19.6 m/s 2 causes the astronaut to experience a g-force of 3. A stationary or constant velocity rocket causes the astronaut to experience a g-force of 1. A rocket accelerating upwards at 49 m/s 2 causes the astronaut to experience a g-force of 6.

6. During launch, the momentum of the propellant expelled downwards (per second) produces a thrust force upwards. For a moving (inertial) frame of reference: i.e. total momentum is unchanged Analyse the changing acceleration of a rocket during launch in terms of the: – Law of Conservation of Momentum – forces experienced by astronauts If this thrust force exceeds the weight of the rocket system, the rocket begins to accelerate upwards. As the rocket expels more and more propellant, the mass of the rocket system decreases. If the thrust force remains constant, Newton’s Second Law tells us that the acceleration will increase. Conservation of momentum tells us that the change in momentum (= Impulse = Force x time ) down produces an Impulse up. So an upwards force (thrust) is produced. The astronauts will experience g-forces produced by this net increasing acceleration while the rockets burn propellant. When the burn finishes, the rocket will continue to move at a constant velocity (subject to drag).

9. He proposed the use of reaction motors that were powered by liquid fuels. He suggested the use of green plants to provide oxygen to space crew and dispose of carbon dioxide Identify data sources, gather, analyse and present information on the contribution of one of the following to the development of space exploration: Tsiolkovsky, Oberth, Goddard, Esnault-Pelterie, O‘Neill or von Braun Tsiolkovsky built the first wind tunnel in Russia which enabled him to observe aerodynamic problems.