Light of wavelength 200 nm shines on a metal surface that requires 4.20 eV to eject an electron. (a) What is the cutoff wavelength for the metal? (b) What is the stopping potential for the 200 nm light? (c) What is the kinetic energy of the fastest ejected electrons? {295 nm, 2.00 V, 295 nm}

In 1995 a research group led by eric cornell and carl wiemann at the university of colorado successfully cooled rubidium atoms to the 20-200 nk temperature range. assuming (incorrectly) that the rubidium atoms behave liké particles of a classical ideal gas, calculate the rms speed of a rubidium atom at a temperature of 112.0 nk. in the experiments one particular isotope of rubidium was used, rubidium-87. the molar mass of this isotope is 86.91 q/mol. tries 0/20 submit answer

The mass of the sun is 1.99×1030kg and its distance to the earth is 1.50×1011m. what is the gravitational force of the sun on the earth?

It is really hard for me right know