Answer:
1456 N
Explanation:
Given that
Frequency of the piano, f = 27.5 Hz
Entire length of the string, l = 2 m
Mass of the piano, m = 400 g
Length of the vibrating section of the string, L = 1.9 m
Tension needed, T = ?
The formula for the tension is represented as
T = 4mL²f²/ l, where
T = tension
m = mass
L = length of vibrating part
F = frequency
l = length of the whole part
If we substitute and apply the values we have Fri. The question, we would have
T = (4 * 0.4 * 1.9² * 27.5²) / 2
T = 4368.1 / 2
T = 1456 N
Thus, we could conclude that the tension needed to tune the string properly is 1456 N
I guess once you input the numbers into the correct places into the equation it would look like this :
PE = 50 * 9.8 * 5.0
PE = 2,450
It goes in this order. Medium, density, viscosity
Yes.
In fact, from the graph we see that the threshold frequency (the minimum energy of the incoming energy needed to extract a photoelectron from the material) is 
(we see it because this is the frequency at which the maximum kinetic energy of the emitted electron is zero).
The incoming photon in this problem has a frequency of 8.0 E14 Hz, so above the threshold frequency, therefore it is enough to extract photoelectrons from the material.
Bohr described the Planetary theory. the atom has a positive nucleus with electrons orbiting around them like planets.
