A Particle Moves with Position Function $\mathbf { r } ( t ) = \left( 21 t - 7 t ^ { 3 } - 5 \right) \mathbf { i } + 21 t ^ { 2 } \mathbf { j }$

question 71

Multiple Choice

A particle moves with position function $\mathbf { r } ( t ) = \left( 21 t - 7 t ^ { 3 } - 5 \right) \mathbf { i } + 21 t ^ { 2 } \mathbf { j }$ .
Find the tangential component of the acceleration vector.

• A) \(a _ { T } = 5 t\)
• B) \(a _ { T } = 542 t\)
• C) \(a _ { T } = 42 t + 5\)
• D) \(a _ { T } = - 55 t\)
• E) \(a _ { T } = 42 t\)

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