You can't determine the mass of an object solely from its weight. Weight is the force of gravity acting on an object's mass. Here's why:

* Weight = Mass x Gravity

To find the mass, you need to know the acceleration due to gravity (g).

Here's how to calculate it:

1. Assume standard gravity: On Earth, the standard acceleration due to gravity is approximately 9.81 m/s².

2. Rearrange the formula: Mass = Weight / Gravity

3. Plug in the values: Mass = 5 N / 9.81 m/s²

4. Calculate: Mass ≈ 0.51 kg

Therefore, the mass of an object weighing 5 newtons on Earth is approximately 0.51 kilograms.

Remember that this calculation is only accurate if the object is on Earth. Gravity varies slightly depending on location and altitude.