Mission NL2 Balanced Forces and the State of Motion
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If you were in a spaceship and fired a cannonball into frictionless space, the amount of force needed to keep the cannonball in motion would ...

Newton's First Law of Motion:
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.
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.

Once in motion an object would continue in motion at constant speed and in the same direction unless acted upon by an unbalanced force. If there is no force to oppose the motion of the cannonball, there is no need to exert a force on the cannonball to keep it in motion. You can kiss this cannonball good-bye.

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