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:

Explanation:
v = Orbital speed = 130 km/s
d = Diameter = 16 ly
r = Radius = 
G = Gravitational constant = 6.67 × 10⁻¹¹ m³/kgs²

As the centripetal force balances the gravitational energy we have the following relation

Mass of the the massive object at the center of the Milky Way galaxy is 
Answer:
42.58kg
Explanation:
By Newton's second law, F = ma.
F is the force being applied, in this case 112N. a is the acceleration, in this case 2.63 m/s^2.
Thus, with some simple algebraic manipulation, we get the mass to equal:
m = F/a = 112N / 2.63 m/s^2 = 42.58kg
Answer:

Explanation:
The Work-Energy Theorem is applied herein:

The number of turns needed to stop the grindstone is:

![n = \frac{(15\,kg)\cdot (0.186\,m)^{2}\cdot [(1.83\,\frac{rev}{min} )\cdot (\frac{2\pi\,rad}{1\,rev} )\cdot (\frac{1\,min}{60\,s} )]^{2}}{4\cdot (0.80)\cdot (8.82\,N)\cdot(0.186\,m)\cdot 2\pi}](https://tex.z-dn.net/?f=n%20%3D%20%5Cfrac%7B%2815%5C%2Ckg%29%5Ccdot%20%280.186%5C%2Cm%29%5E%7B2%7D%5Ccdot%20%5B%281.83%5C%2C%5Cfrac%7Brev%7D%7Bmin%7D%20%29%5Ccdot%20%28%5Cfrac%7B2%5Cpi%5C%2Crad%7D%7B1%5C%2Crev%7D%20%29%5Ccdot%20%28%5Cfrac%7B1%5C%2Cmin%7D%7B60%5C%2Cs%7D%20%29%5D%5E%7B2%7D%7D%7B4%5Ccdot%20%280.80%29%5Ccdot%20%288.82%5C%2CN%29%5Ccdot%280.186%5C%2Cm%29%5Ccdot%202%5Cpi%7D)

Answer:
Explanation:
weight of woman acting downwards = 90 x 10 = 900 N
force by bungee cord in upward direction = 500 N
net force = 900 - 500 = 400 N in downward direction
acceleration in downward direction
= 400 / 90
= 4.44 m /s²