If an object has moved on a straight line without any acceleration, it means that the object's velocity remains constant throughout its motion. This condition is known as uniform motion or constant velocity. There are a few ways to show that an object has moved on a straight line with zero acceleration and zero velocity:
Position-Time Graph: Plot the position of the object on the y-axis against time on the x-axis. If the graph is a straight line with a constant slope (not changing with time), then the object has moved on a straight line without any acceleration. The constant slope represents the constant velocity.
Displacement: Calculate the displacement of the object from its initial position to its final position. If the displacement is non-zero, it means the object has moved. However, to confirm that it moved on a straight line with zero acceleration, you need to check if the displacement is proportional to the time taken. If the displacement divided by the time is a constant value, it indicates uniform motion.
Observational Evidence: If you have observed the object's motion directly, you can note whether it moved in a straight line without changing its speed. If the object maintains a constant speed and does not deviate from a straight path, it suggests uniform motion.
It's important to note that an object moving with zero acceleration and zero velocity implies that no net force is acting on it. In such a case, Newton's first law of motion (the law of inertia) applies, stating that an object at rest or in motion with constant velocity will remain in that state until acted upon by an external force.