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Two blocks are connected by a rope, as shown above. The masses of the blocks are 5 kg for the upper block and 10 kg for the lower block. An upward applied force of magnitude F acts on the upper block. The system is moving and accelerating upward. A pair of scissors cuts the rope. Which of the following describes the motion of the 10 kg block immediately after the rope has been cut?

a. The block continues to move upward but begins to accelerate downward.
b. The block comes to an immediate stop.
c. The block moves upward with the same acceleration as before.
d. The block moves downward with the same acceleration as before.

User BPeter
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1 Answer

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Final answer:

OPTION D.Immediately after the rope is cut, the 10 kg block continues to move upward but begins to accelerate downward due to the force of gravity, as per Newton's first law of motion.

Step-by-step explanation:

The question pertains to the motion of the 10 kg block immediately after the rope connecting it to a 5 kg block is cut while both are accelerating upward due to an applied force on the 5 kg block. When the rope is cut, the 10 kg block will continue to move upward, but it will begin to accelerate downward due to gravity since there will be no more upward forces acting on it (other than the brief inertia). This scenario perfectly encapsulates Newton's first law of motion, where an object in motion remains in motion with the same velocity (and hence the same kinetic energy) unless acted upon by an external force. In this case, after cutting the rope, gravity becomes the unbalanced force causing the 10 kg block to accelerate downward.

The motion of the 10 kg block immediately after the rope is cut depends on the forces acting on the block. In this case, the only force acting on the block is gravity, which pulls it downward with a force equal to the weight of the block. Since there is no upward force to oppose gravity, the block will accelerate downward with the same acceleration it had while moving upward before the rope was cut. Therefore, the correct answer is d. The block moves downward with the same acceleration as before.

User Jayram
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