Find the Scalar Tangential and Normal Components of Acceleration of a Particle

Multiple Choice

Find the scalar tangential and normal components of acceleration of a particle with position vector $\mathbf { r } ( t ) = e ^ { t } ( \cos 8 t , \sin 8 t , 8 )$

A) $a _ { \mathbf { T } } = \sqrt { 65 } e ^ { t }$ , $a _ { \mathrm { N } } = 8 \sqrt { 65 } e ^ { t }$
B) $a _ { \mathbf { T } } = 8 \sqrt { 65 } e ^ { t }$ , $a _ { \mathrm { N } } = \sqrt { 65 } e ^ { t }$
C) $a _ { \mathbf { T } } = 65 e ^ { t }$ , $a _ { \mathrm { N } } ( t ) = 8 e ^ { t }$
D) $a _ { \mathbf { T } } = 8 e ^ { t }$ , $a _ { \mathrm { N } } = 65 e ^ { t }$