Answer: 47.6 m/s
Explanation: Please see attached for the calculation and formula.
Answer:
Found in the nucleus, Has mass of one amu
Things are rubbed against each other
Explanation:
Given that,
Wavelength of the photon, 
Work function of the metal, 
We need to find the maximum kinetic energy of the ejected electrons. It can be calculated using Einstein's photoelectric equation as :






or

So, the maximum kinetic energy of the ejected electrons is 3 ev. Hence, this is the required solution.
Newton's second law of motion:
F=ma

You convert from km/h to m/s by dividing by 3.6:


Then a is:


Then:
F=(980)(2.8)=2744 N