Fig. 1 shows a compressed-air launcher used to test protective packaging for a fragile instrument. Air pressure pushes a piston and launches the package alo...

Fig. 1 shows a compressed-air launcher used to test protective packaging for a fragile instrument. Air pressure pushes a piston and launches the package along a tube. The package has a mass of 0.20 kg and leaves the tube at 14 m/s. A foam box at the end stops it safely. Engineers compare different foam materials by measuring the stopping distance. The pressure gauge is checked before each trial, and students stand behind a safety screen.

(a) Calculate the kinetic energy of the package as it leaves the tube. [2]
(b) Which energy store increases in the foam as the package stops? [1]

The diagram shows a cargo spacecraft using small gas thrusters to turn in space. Two thrusters fire for 4.0 s and provide equal forces in opposite directions. The forces form a couple. The craft does not move sideways, but its angular velocity changes. Engineers use this method to point a communications dish at a star. In space there is almost no air resistance, so the craft continues turning after the thrusters are switched off unless another couple acts.

(a) What is the resultant force on the spacecraft while both thrusters fire? [1]
(b) Which effect do the two forces produce? [1]
(c) Describe what happens to the turning motion after the thrusters stop. [2]
(d) Give one reason why air resistance is very small in space. [1]