Question

An astronaut on a distant planet wants to measure the acceleration due to gravity there by timing pulses (waves) travelling along a wire fixed at each end and with a mass hanging from it (i.e. hanging mass is causing a tension in the wire). She has measured the length and mass of the wire to be 1.60 metres and 3.55 grams. The mass hanging from the wire is 2.9 kgs. If the pulse takes 35.7 milliseconds to travel the full length of the wire, calculate the acceleration due to gravity on the planet without using any astronomical data like the mass of the planet etc. (Units expected m/s/s [i.e. give your numerical answer and then space and then m/s/s])

Answer 1

Frequency of pulse through the wire is given by,

Velocity of pulse through the wire is given by,

Substituting :  

Velocity of pulse through the wire is also given by,

Rearranging   

Acceleration due to gravity,   

Substituting :