Objects in motion tend to stay in straight-line motion at a constant speed, if no unbalanced forces are acting on them
(option: D. straight-line; constant)
Explanation:
This statement is exactly summarized by Newton's first law of motion, which states that:
"For an object moving by uniform motion (=at constant velocity or at rest), the object will maintain its uniform motion if no unbalanced  forces act on it".
This law essentially tells that if there is an object at rest, this will not move unless some external (unbalanced) force is applied on it, and if the object is moving by uniform motion (=constant speed in a straight line), it will continue moving with this motion unless some external (unbalanced) force is applied on it.
This law is generally difficult to prove in real-life situation, because there are always some unbalanced forces acting on objects. For instance, if we roll a ball along a table, if we neglect the friction between the table and the ball, the ball will continue moving with uniform motion forever. Of course this does not occur in real life, only because there is an external (unbalanced) force, the friction, that makes the ball slowing down and eventually stop.
Learn more about Newton laws of motion:
brainly.com/question/11411375
brainly.com/question/1971321
brainly.com/question/2286502
brainly.com/question/2562700
#LearnwithBrainly
Â
