Question 1: Explain in your own words what is meant by an action-reaction force pair, using examples relevant to space exploration.

Answer: An action-reaction force pair consists of two forces that are equal in size but act in opposite directions on two different objects. For example, a rocket expelling gases (action) causes an equal and opposite force pushing the rocket forward (reaction).

Question 1: Describe how a spacecraft's thrusters operate based on the action-reaction principle.

Answer: A spacecraft's thrusters expel gases at high speed in one direction (action), which creates an equal and opposite force (reaction) that propels the spacecraft forward.

Question 2: Why is the action-reaction force pair always acting on different objects in space?

Answer: Because Newton's Third Law states that forces always come in pairs acting on different objects, ensuring the forces are equal and opposite but do not cancel each other out since they act on separate objects.

Question 1: A rocket expels gases at a rate of 2 kg/s with a velocity of 3000 m/s relative to the rocket. Calculate the thrust produced by the engine in newtons.

Answer: Thrust = mass flow rate × exhaust velocity = 2 kg/s × 3000 m/s = 6000 N

Question 2: If a spacecraft with a mass of 5000 kg accelerates at 0.02 m/s² due to a force exerted by its thrusters, what is the magnitude of the force? Use F = ma.

Answer: F = 5000 kg × 0.02 m/s² = 100 N

Question 1: Design a simple experiment to demonstrate the action-reaction principle using a model rocket. Identify the independent and dependent variables, and list safety precautions.

Answer: Experiment involves launching a model rocket where the expulsion of gases (action) causes the rocket to move in the opposite direction (reaction). Variables: gas expulsion velocity (independent), rocket velocity (dependent). Safety precautions include wearing eye protection, conducting the launch in an open area, and ensuring the launch pad is stable.

Question 1: A spacecraft fires its thrusters, resulting in a backward recoil of 10 N while moving forward with a mass of 2000 kg. Describe what this data indicates about the forces involved.

Answer: The backward recoil force of 10 N is the reaction force to the action of the thrusters expelling gases. The equal and opposite force acts on the spacecraft, causing it to accelerate forward, consistent with Newton's Third Law.

Question 1: Explain how the principle of action-reaction forces is utilised in the operation of a spacecraft's ion thrusters. Discuss the advantages and limitations of this technology.

Answer: Ion thrusters operate by expelling ions at high speed in one direction (action), producing an equal and opposite force (reaction) that propels the spacecraft forward. Advantages include high efficiency and continuous thrust, suitable for long-duration missions. Limitations involve low thrust compared to chemical rockets, requiring longer acceleration periods and large power supplies.

Question 1: Describe how action-reaction forces are involved when a spacecraft uses a gravity assist manoeuvre around a planet. What are the implications for spacecraft navigation?

Answer: During a gravity assist, the spacecraft exerts a small force on the planet as it passes close, and in turn, the planet exerts an equal and opposite force on the spacecraft, changing its trajectory and speed. This demonstrates Newton's Third Law and allows for efficient velocity changes without using additional fuel, but precise calculations are essential for navigation.