Newton's first law of motion states that _____ .
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a body at rest ramains at rest if no external force is applied
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a body moving with constant velocity will move with same constant velocity if no external force is applied
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if there is an unbalanced external force acting on body then the body will not remain in state of rest neither move with a constant velocity
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if there is an external force acting on body then the body can not move at constant speed
Newton's first law (law of inertia) states that objects resist changes in motion - a resting object stays at rest, and a moving object continues with constant velocity unless acted upon by an unbalanced external force. Options A, B, and C correctly describe this principle. Option D is false because a body CAN move at constant speed with an external force if the force is perpendicular to motion (like circular motion), or if balanced forces act on it.