Concept explainers
If an object is not moving, does that mean that there are no forces acting on it? Explain.
To describe: Whether no forces are acting on an object when the object is at rest.
Explanation of Solution
Even if an object is at rest, it does not mean no forces are acting on it. Rather consider that the net force on object is 0. That is, all the forces acting on the object sums up to 0.
Consider an example where a box kept on the floor. As the box is in contact with the ground, the ground will exert a normal force on the box, in the direction perpendicular to the ground towards the upward direction.
At the same time the weight force will be acting on the box in downward direction. Hence, the net force sums to be zero and the box rests on the ground.
Conclusion:
Hence, the reason is explained above.
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