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Single Variable Calculus

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Moderate

Speedy Particle

SVCALC-JHK2SG

A particle moves along the x-axis so that at any time $t\ge 0$, its position is given by:

$$s(t)=2\cos { (t) } +1$$

At $t=\dfrac { 5\pi }{ 4 } $, is the particle speeding up or slowing down?

A

The particle is slowing down because at $t=\dfrac { 5\pi }{ 4}$, its velocity and acceleration are both positive.

B

The particle is slowing down because at $t=\dfrac { 5\pi }{ 4}$, its velocity and acceleration are opposite signs.

C

The particle is speeding up because at $t=\dfrac { 5\pi }{ 4}$, its velocity and acceleration are both positive.

D

The particle is speeding up because at $t=\dfrac { 5\pi }{ 4} $, its velocity and acceleration are opposite​ signs.