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.
1.602177e-15 joules are in 10,000 electron volts
Work= force (N) x distance (m)
F= mass (kg) x acceleration (gravity; m/s^2)
for this question, your formula would be
Work= mass (kg) x acceleration (gravity) x distance (m)
a. F=20kg x 9.81 m/s^2 x6 m = 1177.2 J
b. F=25kg x 9.81 m/s^2 x3 m = 735.75 J
c. F=25kg x 9.81 m/s^2 x6 m = 1471.5 J
d. F=50kg x 9.81 m/s^2 x1 m = 490.5 J
Tip:
- If this was a timed test, you could save some time by just multiplying the mass (kg) in the question by the distance because 9.81 is a constant in the formula, you can ignore it (+you're not asked for the final answer). c would still be the largest number
- it would also help if you noticed:
- the distance in c is half that of b but the mass is the same. eliminate b because c is obviously bigger
- a and c have the same distance but 25 is greater than 20; eliminate a
