A point charge, Q = −0.3 µC and m = 3 × 10−16 kg, is moving through the field E = 30az V/m. Use Eq. (1) and Newton’s laws to develop the appropriate differential equations and solve them, subject to the initial conditions at t = 0, v = 3 × 105ax m/s at the origin. At t = 3 µs, find (a) the position P(x, y, z) of the charge; (b) the velocity v; (c) the kinetic energy of the charge.

Respuesta :

Answer:

a).[tex]p(x,y,z)=(0.90m,0,0.135m)[/tex]

b).[tex]v(x,y,z)=(3x10^5 a_{x},0,-9x10^4 a_{z})[/tex]

c).[tex]E_{k}=1.5x10^{-5}J[/tex]

Explanation:

The Newton second law using to determinate position

a).

[tex]F=m*a[/tex]

[tex]F=m*a=m*\frac{d^2Z}{dt^2}[/tex]

[tex]\frac{dZ}{dt}=v_{z}=\frac{q*E}{m}*t[/tex]

[tex]z=\frac{q*E}{2*m}*t^2[/tex]

[tex]z=\frac{(0.3x10{-6}*30}{2*(3x10^{-16})}[/tex]

[tex]z=-1.5x10^{10}*t^2m[/tex]

So at t=3us

[tex]z=-(1.5x10^{10})*(3x10^{-6})^2=-0.135m[/tex]

To x at t=3us

[tex]x=v*t=3x10^5*(3x10^{-6})^2=0.90m[/tex]

[tex]p(x,y,z)=(0.90m,0,0.135m)[/tex]

b).

Velocity now, derive the position can get the velocity of the function so

[tex]z=\frac{q*E}{2*m}*t^2[/tex]

[tex]\frac{dz}{dt}=\frac{q*E}{m}*t[/tex]

[tex]v=\frac{q*E}{m}*t[/tex]

at t=3us

[tex]v=\frac{-0.3x10^{-6}*30}{3x10^{-16}}*3x10^{-6}=-9x10^4\frac{m}{s}[/tex]

so

[tex]v=(3x10^5 a_{x},0,-9x10^4 a_{z})[/tex]

c).

Kinetic energy

[tex]E_{k}=\frac{1}{2}*m*v^2[/tex]

[tex]E_{k}=\frac{1}{2}*3x10^{-16}*(1.13x10^5)^2=1.5x10^{-5}J[/tex]