# Math Help - Vector Acceleration

1. ## Vector Acceleration

Find the acceleration vector in terms of ur and u x.

r = a(4 - cos x) and dx/dt = 6

v(t) = r' (t) = a(4 +sinx) + (4-cosx) (1)

ll v(t) ll = sqrt( a^2 + (4-cox)^2) = sqrt(a^2 + (16 - cos x)^4)

= 4sqrt( a^2 + (-cosx)^4)

a(t) = r " (t) = ????

u
r = V dot a / ll v ll = ????

* I think I might be off??? Any assistance???

2. Originally Posted by sderosa518
[SIZE=2]Find the acceleration vector in terms of ur and u x.

r = a(4 - cos x) and dx/dt = 6

v(t) = r' (t) = a(4 +sinx) + (4-cosx) (1)
I presume a is your accelerion? Then
$v(t) = r'(t) = a'(4 - cos(x)) + a(4 + sin(x))$

Also, have a care when finding the norm of v(t). You misapplied it.

-Dan