Mission NL2 Balanced Forces and the State of Motion
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The oil drop diagram below depicts the motion of a rightward-moving object (or a leftward-moving object). Which one of the force diagrams is ...

An object at rest will stay at rest; an object in motion will stay in motion with the same speed and direction, unless acted upon by an unbalanced force.

It is a common misconception to think that a force causes a motion in a given direction. This misconception leads to the further misconception that a motion to the right requires an unbalanced force to the right. But don't be fooled! Forces, when unbalanced, cause accelerations. The direction of the acceleration is the same as the direction of the unbalanced force. Only an acceleration to the right would require an unbalanced force to the right. A motion at constant speed in a given direction is consistent with a balance of forces. Make O' Isaac proud and answer this one right.
