Answer:

Explanation:
It is given that,
Initially, the electron is in n = 7 energy level. When it relaxes to a lower energy level, emitting light of 397 nm. We need to find the value of n for the level to which the electron relaxed. It can be calculate using the formula as :


R = Rydberg constant, 

Solving above equation we get the value of final n is,

or

So, it will relax in the n = 2. Hence, this is the required solution.
Answer:
Technician b is correct.
Explanation:
Crimping cable allows a firm connection in mechanical terms and allows a low resistance path for the signal or the current flow, solder although it is better in terms of electrical conduction, can be impractical if the cable is subjected to excessive movement.
A crimped cable with excessive movement can also be easily broken at the ends, where it joins the part of the cable that is crimped, for this reason, a cable that is in excessive motion is recomended to be spliced by joining cable with cable
.
In order to decide which metod is better for splicing cables its necessary to evaluate each situation separatly.
Answer:
(a) 0 (b) 
Explanation:
Given that,
Mass of a supertanker, 
The engine of a generate a forward thrust of, 
(a) As the supertanker is moving with a constant velocity. We need to find the magnitude of the resistive force exerted on the tanker by the water. It is given by :
F = ma, a is the acceleration
For constant velocity, a = 0
So, F = 0
(b) The magnitude of the upward buoyant force exerted on the tanker by the water is equal to the weight of the ship.
F = mg

Hence, this is the required solution.
Answer: 1.9 m/s
Explanation:
1) Data:
height, y = 0
range, x = 0.77m
angle, α = 45°
question, horizontal velocity, Vox = ?
2) Physical principles and formulas
Projectile motion.

3) Solution


Factor
![0=t[V_0sin(45)-gt/2]](https://tex.z-dn.net/?f=%200%3Dt%5BV_0sin%2845%29-gt%2F2%5D%20)
Discard t = 0 and solve for the other factor:
![gt/2=V_0sin(45)\\ \\ V_0= gt/(2sin(45))=9.81[0.77/V_{0}cos(45)]/[2sin(45)]\\ \\ V_0^2=9.81[0.77/(2cos(45)sin(45)=9.81[0.77/sin(90)]=7.55\\ \\ V_0}=\sqrt{7.55} =2.8](https://tex.z-dn.net/?f=%20gt%2F2%3DV_0sin%2845%29%5C%5C%20%5C%5C%20%20V_0%3D%20gt%2F%282sin%2845%29%29%3D9.81%5B0.77%2FV_%7B0%7Dcos%2845%29%5D%2F%5B2sin%2845%29%5D%5C%5C%20%5C%5C%20V_0%5E2%3D9.81%5B0.77%2F%282cos%2845%29sin%2845%29%3D9.81%5B0.77%2Fsin%2890%29%5D%3D7.55%5C%5C%20%5C%5C%20V_0%7D%3D%5Csqrt%7B7.55%7D%20%3D2.8%20%20)
Find Vx:
![Vx=V_{0x}=V_{0}cos(45)=2.75(\sqrt{2} /2]=1.9](https://tex.z-dn.net/?f=%20Vx%3DV_%7B0x%7D%3DV_%7B0%7Dcos%2845%29%3D2.75%28%5Csqrt%7B2%7D%20%2F2%5D%3D1.9%20%20)
Vx = 1.9m/s ← answer