Based on Newton's second law of motion, \( F = ma \) (where \( F \) is force, \( m \) is mass, and \( a \) is acceleration), the relationship between force and acceleration is that they are directly proportional. This means that as force increases, acceleration also increases, resulting in an upward-sloping line on a graph.
Therefore, the phrase that best describes this relationship is:
an upward-sloping line drawn on a graph with acceleration shown on the y-axis and force shown on the x-axis.