1. What is speed?
The speed of an object is the distance the object moves per unit of time.
Speed may be written as an equation Speed = Distance Time
• SI units of distance include kilometers (km), meters (m), and centimeters (cm).
• Units of time used include hours (h) or seconds (s).
1. Identify Write an example of an appropriate choice of units to express the speed of an ant crawling along a sidewalk.

2. What is velocity?
The speed of an object in a given direction is its velocity.
The velocity of an object changes when either its speed or its direction of motion changes.
2. Apply Write an example of the velocity of a moving bicycle and an example of a change in the velocity of the bicycle.

3. What is acceleration?
Acceleration is the rate at which velocity changes.
Acceleration occurs whenever an object has a change in speed or direction.
Positive acceleration occurs when an object speeds up. Negative acceleration, or deceleration, occurs when an object slows down.
A change in direction, with or without a change in speed, is also acceleration.
3. Explain Why is a decrease in speed an example of acceleration?

4. How can you differentiate among speed, velocity, and acceleration?
Speed is measured using a unit of distance divided by a unit of time.
Velocity is described using speed and direction of motion.
Acceleration refers to increasing speed, decreasing speed, or changing direction.
4. Differentiate In your own words, differentiate among speed, velocity, and acceleration.