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Question
An object experiences a net zero external unbalanced force. Is it possible for the object to be travelling with a non-zero velocity? If yes, state the conditions that must be placed on the magnitude and direction of the velocity. If no, provide a reason.
Solution
Yes, when the external unbalanced force on an object is zero, the object can travel at a non-zero velocity. The necessary conditions include:
- The object should already be moving at a uniform speed along a straight line.
- There should be no change in the magnitude of velocity and also no change in the direction of motion.
- The resistance to motion due to air must be zero.
- The resistance to motion due to friction between the object and the ground must be zero.
If one of the four conditions listed above is not met, the answer will be no. This is because an imbalanced external force is required to initiate the motion as well as any subsequent changes (decrease/increase) in velocity.
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