This is an interesting (read tricky!) variation of Rydberg Eqn calculation.
Rydberg Eqn: 1/λ = R [1/n1^2 - 1/n2^2]
Where λ is the wavelength of the light; 1282.17 nm = 1282.17×10^-9 m
R is the Rydberg constant: R = 1.09737×10^7 m-1
n2 = 5 (emission)
Hence 1/(1282.17 ×10^-9) = 1.09737× 10^7 [1/n1^2 – 1/25^2]
Some rearranging and collecting up terms:
1 = (1282.17 ×10^-9) (1.09737× 10^7)[1/n2 -1/25]
1= 14.07[1/n^2 – 1/25]
1 =14.07/n^2 – (14.07/25)
14.07n^2 = 1 + 0.5628
n = √(14.07/1.5628) = 3
Answer:
You are asked to design a cylindrical steel rod 50.0 cm long, with a circular cross section, that will conduct 170.0 J/s from a furnace at 350.0 ∘C to a container of boiling water under 1 atmosphere.
Explanation:
Given Values:
L = 50 cm = 0.5 m
H = 170 j/s
To find the diameter of the rod, we have to find the area of the rod using the following formula.
Here Tc = 100.0° C
k = 50.2
H = k × A × ![\frac{[T_{H -}T_{C} ] }{L}](https://tex.z-dn.net/?f=%5Cfrac%7B%5BT_%7BH%20-%7DT_%7BC%7D%20%5D%20%7D%7BL%7D)
Solving for A
A = ![\frac{H * L }{k * [ T_{H}- T_{C} ] }](https://tex.z-dn.net/?f=%5Cfrac%7BH%20%2A%20L%20%7D%7Bk%20%2A%20%5B%20T_%7BH%7D-%20T_%7BC%7D%20%5D%20%7D)
A = ![\frac{170 * 0.5}{50.2 * [ 350 - 100 ]}](https://tex.z-dn.net/?f=%5Cfrac%7B170%20%2A%200.5%7D%7B50.2%20%2A%20%5B%20350%20-%20100%20%5D%7D)
A =
= 6.77 ×
m²
Now Area of cylinder is :
A =
d²
solving for d:
d = 
d = 9.28 cm
The crate moves at constant velocity, this means that its acceleration is zero, so the net force acting on the crate is zero (Newton's second law).
There are only two forces acting on the crate: the force F applied by the worker and the frictional force, acting in the opposite direction:

, where

is the coefficient of friction and

is the mass of the crate. Since the net force should be equal to zero, the two forces must have same magnitude, so we have:

And so, this is the force that the worker must apply to the crate.
Answer:
a) t= 4.81 s,and t= 23.51.
b)d=6.88 m
c)v=4.8 m/s
Explanation:
Acceleration of train ,a= 0.6 m/s²
u = 0 m/s
Your speed ,V= 8.5 m/s
Lets take after t time he you catch the train
Distance travel by train in t time
----------1
d= V ( t- 4)
d= 8.5 ( t- 4) --------2
By equating equation 1 and 2
0.3 t² = 8.5 ( t- 4)
0.3 t² -8.5 t + 34 = 0
t= 4.81 s and t= 23.51
It means that you will catch train after t= 4.81 s,and t= 23.51.
t=23.51 sec means that you will catch the train after 23.51 sec also because acceleration of train is low.
Distance travel
d= 8.5 ( t- 4)
t= 4.81 s
d= 8.5 ( 4.81- 4) m
d=6.88 m
Lets speed = v
0.3 t² = v ( t- 4)
0.3 t² - v t + 4 v = 0
To have one solution

D= 0 Should be zero.
v²- 4 x 0.3 x 4 v
v = 4 x 0.3 x 4
v=4.8 m/s