An object that moves with changing speed is one whose rate of motion is not constant. Examples include a car accelerating from rest to a higher speed and a ball being thrown into the air.
Speed is the rate at which an object changes its location. An object that moves with changing speed is one whose rate of motion is not constant.
This means that its speed is not staying the same, but rather increasing or decreasing over time.
For example, a car accelerating from rest to a higher speed is an object that moves with changing speed. Initially, its speed is low and gradually increases until it reaches the desired higher speed.
Another example is a ball being thrown into the air. As the ball goes up, its speed decreases due to the influence of gravity, and when it comes back down, its speed increases as gravity accelerates it towards the ground.