If a car accelerates from rest, the acceleration is defined as the rate of change of:

The acceleration of a car from rest is defined as the rate of change of its velocity. This means how quickly the speed of the car is increasing over a certain period of time. Here are the steps to understand this:

1. Start with the definition of acceleration: Acceleration is a measure of how quickly the velocity of an object changes.

2. Apply this definition to a car at rest: When a car is at rest, its initial velocity is zero. As it starts to move, its velocity increases - it goes from zero to a certain speed.

3. Understand the rate of change: The rate of change is simply how much something changes over a certain period of time. In this case, it's how much the velocity of the car changes as it accelerates from rest.

4. Put it all together: So, the acceleration of a car from rest is the rate at which its velocity (speed) increases over time. If the car accelerates quickly, this means its speed is increasing rapidly. If it accelerates slowly, its speed is increasing at a slower rate.