What is the maximum speed of the piston?
4.2 m s−14.2\text{ m s}^{-1}4.2 m s−1
13 m s−113\text{ m s}^{-1}13 m s−1
26 m s−126\text{ m s}^{-1}26 m s−1
52 m s−152\text{ m s}^{-1}52 m s−1
