Answer:
2 and a half hours
Explanation:
Nancy rides her bike at 10 miles per hour. After the first hour, she would have ridden 10 miles. After the second hour, she would hvae ridden 20 miles. She needs to ride 5 more miles, which is half of her 10 miles that she rides every hour. Since it is half of her speed of miles per hour, it will take her another half an hour to ride the 5 miles. Added together, Nancy takes 2 and a half hours.
The answer is n= 6.
What is Balmer series?
The Balmer series is the portion of the emission spectrum of hydrogen that represents electron transitions from energy levels n > 2 to n = 2. These are four lines in the visible spectrum. They are also known as the Balmer lines. The four visible Balmer lines of hydrogen appear at 410 nm, 434 nm, 486 nm and 656 nm.
For the Balmer series, the final energy level is always n=2. So, the wavelengths 653.6, 486.1, 434.0, and 410.2 nm correspond to n=3, n=4, n=5, and n=6 respectively. Since the last wavelength, 410.2 nm, corresponds to n=6, the next wavelength should logically correspond to n=7.
To solve for the wavelength, calculate the individual energies, E2 and E7, using E=-hR/(n^2). Then, calculate the energy difference between E2 (which is the final) and E7 (which is the initial). Finally, use lamba=hc/E to get the wavelength.
To learn more about emission spectrum click on the link below:
brainly.com/question/24213957
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Answer:
a) 17.49 seconds
b) 13.12 seconds
c) 2.99 m/s²
Explanation:
a) Acceleration = a = 1.35 m/s²
Final velocity = v = 85 km/h = 
Initial velocity = u = 0
Equation of motion
Time taken to accelerate to top speed is 17.49 seconds.
b) Acceleration = a = -1.8 m/s²
Initial velocity = u = 23.61\ m/s
Final velocity = v = 0
Time taken to stop the train from top speed is 13.12 seconds
c) Initial velocity = u = 23.61 m/s
Time taken = t = 7.9 s
Final velocity = v = 0
Emergency acceleration is 2.99 m/s² (magnitude)
