You will learn the meaning of speed, velocity and average velocity.

### Key Equations

**Average Velocity**

\begin{align*}v_{avg} & = \frac{\boldsymbol{\Delta} x}{\Delta t} \\ \end{align*}

#### Example 1

Pacific loggerhead sea turtles migrate over 7,500 miles (12,000 km) between nesting beaches in Japan and feeding grounds off the coast of Mexico. If the average speed of a loggerhead is about 45 km/day, how long does it take for it to complete the distance of a one-way migration?

*Question:* \begin{align*}t = ?\end{align*} [days]

*Given:* \begin{align*}d = 12,000 \ km\end{align*}

\begin{align*}{\;} \qquad v_{avg} = 45 \ km/day\end{align*}

*Equation:* \begin{align*}v_{avg} = \frac{d}{t}\end{align*} therefore \begin{align*}t = \frac{d}{v_{avg}}\end{align*}

*Plug n’ Chug:* \begin{align*}t = \frac{d}{v_{avg}} = \frac{12,000 \ km}{45 \ km/day} = 267 \ days\end{align*}

*Answer:* \begin{align*}\boxed{\mathbf{267 \ days}}\end{align*}

### Watch this Explanation

### Simulation

### Time for Practice

- Two cars are heading right towards each other, but are 12 km apart. One car is going 70 km/hr and the other is going 50 km/hr. How much time do they have before they collide head on?
- You drive the 10 miles to work at an average speed of 40 mph. On the way home you hit severe traffic and drive at an average speed of 10 mph. What is your average speed for the trip?

**Answers**

1. 0.1 hours = 6 minutes

2. 16 mph