Answer:
70 kg is the mass of the object
Explanation:
This question can be solved with this simple formula:
Weight force = mass . gravity
686 N = mass . 9.8 m/s²
686 N / 9.8 m/s² = mass → 70 kg
Note → 1N = 1 kg . m / s²
550 nm is in the visible spectrum. 400 nm is in the ultra-violet spectrum. The shorter the wavelength, the bigger the energy of the light photon emitted. Therefore a star that emits 400 nm photons, is hotter than the Sun. A star that is hotter is either bigger than the Sun (and has about the same age), either younger than the Sun (and has about the same dimension).
Therefore a star that radiates at 400 nm would be hotter, bigger and younger than the Sun.
I think it might be heat energy. light transforms into heat energy