Speed is the rate at which an object changes its position and is a scalar quantity. Velocity is the rate at which an object changes its position in a specific direction and is a vector quantity. Acceleration is the rate at which an object changes its velocity and is a vector quantity.
When the velocity of an object is zero, it means that the object is not moving. When the acceleration of an object is less than zero, it means that the object is slowing down. Therefore, the speed of the object cannot increase when the velocity is zero and the acceleration is less than zero.
