Lesson 10.3: Acceleration measures how fast velocity changes

Lesson Focus

This lesson introduces acceleration: the rate at which an object's velocity changes. You'll discover how speeding up, slowing down, and turning are all forms of acceleration, a concept essential for understanding motion in our universe.

Learning Objectives

• Describe how acceleration is directly related to any change in an object's velocity, whether in speed or direction.
• Learn how to calculate acceleration using an object's initial velocity, final velocity, and the time interval of change.

Objects accelerate when their velocity changes. This can be a change in speed, direction, or both. Therefore, acceleration is the rate at which velocity changes. If an object moves at a constant speed in a straight line, its acceleration is zero. Why is a car turning a corner accelerating?

The direction of acceleration determines how motion changes. Acceleration in the same direction as motion causes an object to speed up. Acceleration in the opposite direction causes it to slow down (negative acceleration). Acceleration at a right angle makes it turn. This shows their relationship from the previous lesson summary.

We can calculate acceleration by measuring how much an object's velocity changes over a specific time. We use the formula a = (vfinal - vinitial) / t, where 'a' is acceleration (m/s²). This calculation gives us a precise value for how quickly motion is changing.

A velocity-time graph illustrates an object's acceleration. A line sloping upward shows positive acceleration (speeding up). A horizontal line means zero acceleration (constant velocity). A line sloping downward indicates negative acceleration (slowing down). The steepness of the slope reveals how great the acceleration is. This is the visualization of the previous lesson summary.