Respuesta :
Answer:
(a) 1.298 * 10^(-4) J
(b) 5.82 * 10^6 m/s
Explanation:
Parameters given:
Electric field, E = 640 N/C
Distance traveled by electron, r = 15 cm = 0.15 m
Mass of electron, m = 9.11 * 10^(-31) kg
Electric charge of electron, q = 1.602 * 10^(-19) C
(a) The kinetic energy of the electron in terms of Electric field is given as:
K = (q² * E² * r²) / 2m
Therefore, Kinetic energy, K, is:
K = [(1.602 * 10^(-19))² * 640² * 0.15²] / [2 * 9.11 * 10^(-31)]
K = {23651.981 * 10^(-38)} / [18.22 * 10^(-31)]
K = 1298.13 * 10^(-7) J = 1.298 * 10^(-4) J
(b) To find the final velocity of the electron, we have to first find the acceleration of the electron. This can be gotten by using the equations of force.
Force is generally given as:
F = ma
Electric force is given as:
F = qE
Therefore, equating both, we have:
ma = qE
a = (qE) / m
a = (1.602 * 10^(-19) * 640) / (9.11 * 10^(-31))
a = 112.54 * 10^(12) m/s² = 1.13 * 10^(14) m/s²
Using one of the equations of motion, we have that:
v² = u² + 2as
Since the electron started from rest, u = 0 m/s
Therefore:
v² = 2 * 1.13 * 10^(14) * 0.15
v² = 3.39 * 10^(13)
v = 5.82 * 10^6 m/s
The velocity of the electron after moving a distance of 15 cm is 5.82 * 10^6 m/s.
(a) The kinetic energy of the electron is 1.53×10⁻¹⁷ J
(b) The final speed of the electron is 5.8×10⁶ m/s
Kinetic energy and final speed:
The electron is under motion due to the electrostatic force F produced by the electric field E = 640 N/C.
The equation of motion of the electron can be written as:
F = qE
⇒ ma = qE
where q = 1.6×10⁻¹⁹ C is the charge on the electron
m = 9.1×10⁻³¹ kg is the mass of the electron
and a is the acceleration.
So,
a = qE/m
a = 1.6×10⁻¹⁹×640 / 9.1×10⁻³¹
a = 1.12×10¹⁴ m/s²
The initial speed of the electron is zero, so u = 0
From the third equation of motion:
v² = u² + 2as
where v is the final speed,
and s is the distance traveled = 15cm = 0.15m
v² = 0 + 2× 1.12×10¹⁴×0.15
v = 5.8×10⁶ m/s
So the Kinetic energy of the electron is:
KE = ¹/₂mv²
KE = 0.5×9.1×10⁻³¹×(5.8×10⁶)²
KE = 1.53×10⁻¹⁷ J
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