No, an object moving at a constant speed in a straight line does not need a force acting on it to maintain its uniform motion. This is due to Newton's First Law of Motion, also known as the Law of Inertia.

Here's why:

* Inertia: Inertia is the tendency of an object to resist changes in its motion. An object at rest wants to stay at rest, and an object in motion wants to stay in motion.

* No Net Force: If there is no net force acting on an object, its inertia will keep it moving at a constant speed in a straight line.

* Force and Change: Forces cause changes in motion. If there is a force, it will either:

* Start an object moving (if it was at rest).

* Stop an object moving (if it was in motion).

* Change the direction or speed of an object that's already in motion.

Example: Imagine pushing a box across a perfectly smooth, frictionless surface. Once you stop pushing, the box will continue to slide at a constant speed in the same direction because there's no force to slow it down.

Real World: In the real world, there's almost always some friction present, so a force is needed to overcome friction and keep an object moving at a constant speed. However, the principle of inertia still applies.