* Speed is the rate at which an object changes its position. If an object is stationary, its speed is zero.

* Acceleration is the rate at which an object changes its *velocity*. Velocity includes both speed and direction.

Here's a common example:

Imagine a ball thrown straight up into the air. At the very top of its trajectory, for a split second, the ball's speed is zero (it's stopped moving upward before starting to fall back down). However, at that exact moment, gravity is still acting on the ball, causing it to accelerate downwards.

Other scenarios:

* A car at a red light: The car is stopped (speed = 0), but the driver pressing the brake pedal is causing the car to decelerate (acceleration in the opposite direction of motion).

* An object on a spring: When the object reaches its maximum displacement from its equilibrium point, its speed is momentarily zero. However, the spring's force is still acting on it, causing it to accelerate back towards the equilibrium position.

In summary: An object can have zero speed and non-zero acceleration if it is in the process of changing its velocity, either by changing its speed or its direction.