Answer:
<h2>
E = 2.8028*10⁻¹⁹ Joules</h2>
Explanation:
The minimum energy needed to eject electrons from a metal with a threshold frequency fo is expressed as E = hfo
h = planck's constant
fo = threshold frequency
Given the threshold frequency fo = 4.23×10¹⁴ s⁻¹
h = 6.626× 10⁻³⁴ m² kg / s
Substituting this value into the formula to get the energy E
E = 4.23×10¹⁴ * 6.626 × 10⁻³⁴
E = 28.028*10¹⁴⁻³⁴
E = 28.028*10⁻²⁰
E = 2.8028*10⁻¹⁹ Joules
In this problem, we apply the equation regarding kinematics expressed as vf^2 = v0^2 + 2as vf eventually becomes zero because the ball stops in the end. a = -9.8 m/s2s = 2 metres this time
This gives initial velocity, vo equal to 6.26m/s
now 6.26-(-8.85) = 15.11m/s
change in velocity/change in time = average acceleration 15.11/(12/1000) = 1259.167 m/s^2
<u>Answer:</u>
A perfect example of wave reflection is an <u>echo</u>.
<u>Explanation:</u>
A wave reflection takes place when waves cannot pass through a surface and in turn they bounce back. It is not necessary that wave reflections can only happen with sound waves, they can also take place in light waves. Also, the waves which are reflected have the same frequency as the original wave, but their direction is different. When a wave strikes an object in the same angle, they bounce back straight but when they hit an object with different angle, their direction changes.
Honestly, I am quite confused with what Nv stands for because there is no element with that symbol. However, I still get the concept of finding the average molecular mass of an element. Let's just assume that nv stands for a specific type of element and it has two isotopes: nv-293 and nv-295. Isotopes have the same number of protons but differ in mass number (protons+neutrons).
To find the average atomic weight, just multiply the individual weights with the respective composition of the isotope. Since there are only two isotopes, they constitute 50% each. So, the average atomic weight is
(50%)(293.15 amu) + (50%)(<span>295.30 amu) = 294.225 amu
Hence, the atomic weight of nv is 294.225 atomic mass units.</span>
