IB Physics-Paper 2-Topic 5-2 and 6-Qc#16-Ion-thrust engines-Conservation of momentum

Ion-thrust engines can power spacecraft. In this type of engine, ions are created in a chamber and expelled from the spacecraft. The spacecraft is in outer space when the propulsion system is turned on. The spacecraft starts from rest. The mass of ions ejected each second is 6.6 × 10 kg and the speed of each ion is 5.2 × 10 m s . The initial total mass of the spacecraft and its fuel is 740 kg. Assume that the ions travel away from the spacecraft parallel to its direction of motion.
a. Determine the initial acceleration of the spacecraft.
An initial mass of 60 kg of fuel is in the spacecraft for a journey to a planet. Half of
the fuel will be required to slow down the spacecraft before arrival at the
destination planet.
b. Estimate the maximum speed of the spacecraft.
c. Outline why scientists sometimes use estimates in making calculations.
In practice, the ions leave the spacecraft at a range of angles as shown.
d. Outline why the ions are likely to spread out.
e. Explain what effect, if any, this spreading of the ions has on the
acceleration of the spacecraft.
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