Which choice of laboratory equipment would enable you to determine the gravity of an unknown planet you are visiting?
a) Stopwatch, 50 cm of string, 100 g mass
b) Spring with k=20 N/m, stopwatch, 100 g mass
c) 50 cm of string, ruler, spring with k=20 N/m
d) 100 g mass, ruler, 50 cm of string
e) Stopwatch, ruler, spring with k=20 N/m