If no forces act on an object, the object does not change its motion and moves at a ______ speed in a given direction.

If no forces act on an object, the object does not change its motion and moves at a ______ speed in a given direction.

• A. Constant
• B. Rest
• C. Direction
• D. Straight line

Answer: (A)

When no net force acts on an object, its motion doesn’t change—this is inertia. The object’s velocity stays the same, which means both its speed and its direction remain constant. Since the sentence specifies movement in a given direction, the speed must remain constant in that direction. Rest would mean no movement at all, which isn’t the situation here, and while the motion would be in a straight line, the blank is describing speed, not the path. So the best fit is that the speed remains constant.

When no net force acts on an object, its motion doesn’t change—this is inertia. The object’s velocity stays the same, which means both its speed and its direction remain constant. Since the sentence specifies movement in a given direction, the speed must remain constant in that direction. Rest would mean no movement at all, which isn’t the situation here, and while the motion would be in a straight line, the blank is describing speed, not the path. So the best fit is that the speed remains constant.