What did Galileo observe by placing two inclined planes facing each other and rolling down a marble ball from top end of one of them?
One mark Question.
Answers
Answer:
he observed that a ball rolled down one plane from a particular height, goes to the same height on the other plane before coming to rest. This happened irrespective of the inclination of the planes.
He observed that if the slope of second plane is zero i.e. horizontal, then the ball will keep moving untill it reaches the same hight h, but since there is no increase in height, it keeps rolling till infinity.
This is the same result as the Newton first law of motion.
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"The ball again rises to the same height from which it was released. Now, however, the ball must roll a greater distance up the right incline before coming to a stop for an instant at the top of its journey."
It is because an unbalanced force is required to change the motion of the object but no force is needed to sustain the uniform motion of the object.
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Galileo argued that when the marble is released from inclined plane, it would roll down the slope and go up on the opposite side of inclined plane to the same height from which it was released. If the inclinations of the planes on both sides are equal then the marble will climb the same distance that it covered while rolling down.
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If the angle of inclination of the right-side (opposite) plane were gradually decreased, then the marble would travel further distances till it reaches the original height. It is because marble will try to reach to same height that it was released.
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If the right-side plane were ultimately made horizontal (that is, the slope is reduced to zero), the marble would continue to travel forever trying to reach the same height that it was released from.
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The unbalanced forces on the marble in this case are zero. It thus suggests that an unbalanced (external) force is required to change the motion of the marble but no net force is needed to sustain the uniform motion of the marble.
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In practical situations it is difficult to achieve this situation because of the presence of the frictional force acting opposite to the direction of motion. Thus, in practice the marble stops after travelling some distance