(a) Find the position vector of a particle that has the given acceleration and the specified initial velocity and position. a(t) = 20t i + sin(t) j + cos(2t) k, v(0) = i, r(0) = j

Respuesta :

Answer:

[tex]r(t)=(\frac{10t^3}{3}+t)i+(-sint+t+1)j+(\frac{-cos2t}{4}+\frac{1}{4})k[/tex]

Explanation:

a(t)=20t i+sin(t) j +cos(2t) k

v(t)=[tex]\int\limits^a_b {a(t)} \, dt[/tex]

=[tex](10t^2+c_1)i+(-cost+c_2)j+\frac{sin2t}{2}k[/tex]---------------eqn 1

given v(0)=i

i=[tex]c_1i+(-1+c_2)j+(0+c_3)k[/tex]

[tex]c_1=1[/tex]   [tex]c_2=1[/tex]  [tex]c_3=0[/tex]

from equation 1

V(t)=[tex](10t^2+c_1)i+(-cost+c_2)j+\frac{sin2t}{2}k[/tex]----------eqn 2

now r(t)=[tex]\int\limits^a_b {v (t)} \, dt[/tex]

[tex](\frac{10t^3}{3}+t+c_1)i+(-sint+t+c_2)j+(\frac{-cos2t}{4}+c_3)k[/tex]

given r(0)=j

0i+1j+ok = [tex]c_1i+c_2j+(\frac{-1}{4}+c_3)k[/tex]

[tex]c_1=0[/tex]  [tex]c_2=0[/tex]  [tex]c_3 =  \frac{1}{4}[/tex]

[tex]r(t)=(\frac{10t^3}{3}+t)i+(-sint+t+1)j+(\frac{-cos2t}{4}+\frac{1}{4})k[/tex]