Motion

Example 3: USS Nimitz.

The Question: The USS Nimitz The USS Nimitz is the lead ship in the supercarrier class in the US Navy. It carries 3200 sailors and aviators and supports nearly 100 fixed wing aircraft. The Nimitz has a top speed that’s classified, but it is at least 30 knots (34 mph).

Suppose it was cruising at that speed in open water and came to a complete stop (an unusual maneuver) in 30 minutes, what would be its deceleration if it’s constant?

The Answer:

What do we know:

\begin{align} v_0 &=30 \text{ knots} = 15.4 \text{ m/s} \nonumber \\ v &= 0 \nonumber \\ t &=30 \text{ min}=1800 s \nonumber \end{align}

So we need to find the acceleration — which we expect to be negative because it’s slowing down:

\begin{align} v &= v_0+at \nonumber \\ a &= \frac{v-v_0}{t} \nonumber \\ &= \frac{0-15.4}{1800} = -\frac{15.4}{1800} \nonumber \\ a &= -0.009 \text{ m/s}^2 \nonumber \end{align}