Question

An astronaut in a space craft a long way from any strong gravitational fields needs to measure a mass. He attaches a 2 kg mass to a spring and find that the system vibrates at a frequency of 45.3 Hz. He then attaches his second, unknown mass, to the spring and finds that it then vibrates at 20.3 Hz. What is the unknown mass?

[This type of system is called an inertial balance since it measures mass entirely using inertia without requiring any gravitational field.]

Answer 1