The formular for determinatio of mass number is this:
Mass number = number of proton + number of neutron
From the question, we are told that:
Mass number = 39
Proton number = 19
Number of proton = ?
Number of neutron = mass number - number of proton
Number of neutron= 39 - 19 = 20
Therefore, number of neurtron = 20.
Answer:
Explanation:
Due to the law of conservation of energy, the energy of the emitted X-ray photon is equal to the energy lost by the electron.
The initial kinetic energy of the electron is:
The electrons decelerates to 3/4 of its speed, so the new speed is
So the final kinetic energy is
So, the energy lost by the electron, which is equal to the energy of the emitted photon, is
The wavelength of the photon is related to its energy by
where h is the Planck constant and c the speed of light. Substituting E, we find
A simple machine can make work easier by reduce the amount of energy needed to perform a task, therefore, B. it magnifies the potential energy so that the kinetic energy is greater is the correct answer:)
Answer:
v_f = 3 m/s
Explanation:
From work energy theorem;
W = K_f - K_i
Where;
K_f is final kinetic energy
K_i is initial kinetic energy
W is work done
K_f = ½mv_f²
K_i = ½mv_i²
Where v_f and v_i are final and initial velocities respectively
Thus;
W = ½mv_f² - ½mv_i²
We are given;
W = 150 J
m = 60 kg
v_i = 2 m/s
Thus;
150 = ½×60(v_f² - 2²)
150 = 30(v_f² - 4)
(v_f² - 4) = 150/30
(v_f² - 4) = 5
v_f² = 5 + 4
v_f² = 9
v_f = √9
v_f = 3 m/s
Brass is an alloy, a combination of two metals, and aluminum is a pure metal
