There are some missing data in the text of the problem. I've found them online:
a) coefficient of friction dry steel piston - steel cilinder: 0.3
b) coefficient of friction with oil in between the surfaces: 0.03
Solution:
a) The force F applied by the person (300 N) must be at least equal to the frictional force, given by:

where

is the coefficient of friction, while N is the normal force. So we have:

since we know that F=300 N and

, we can find N, the magnitude of the normal force:

b) The problem is identical to that of the first part; however, this time the coefficienct of friction is

due to the presence of the oil. Therefore, we have:
Answer:
a) 1.2*10^-7 m
b) 1.0*10^-7 m
c) 9.7*10^-8 m
d) ultraviolet region
Explanation:
To find the different wavelengths you use the following formula:

RH: Rydberg constant = 1.097 x 10^7 m^−1.
(a) n=2

(b)

(c)

(d) The three lines belong to the ultraviolet region.
<span>work will be equal to the potential energy gained by the person in climbing the stairs.
work= potential energy gained = mgh
W= 75kg*9.8m/s2*2.50m= 1837.5 J</span>