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Newton's 1st law states " EVERY BODY continues in its state of rest or of uniform motion in a straight line unless it is compelled by ext. force to change dat state. "suppose a time bomb is placed somewhere. It is at rest and we conclude dat it will continue to remain so. But after some time , the bomb explodes & da splinters run here and there. Obviously the body ( i,e da bomb or whatever remains of it ) can no longer said to be at rest as it was some time ago. And no EXTERNAL FORCE was put.
Comments (53)
In case of the bomb ..the chemical energy was converted into mechanical energy .
But as u can see...there was no external force ..the bomb was split into slices ..BUT THE CENTRE OF MASS REMAINED AS IT IS.
there was no ext torque ..there was no ext force.. hence COM remained as it is.
hmm. not always. A body can be made to spin by applying a torque but its COM will be at rest.The law says that a body will remain at rest unless a force acts on it, and not that if a force acts on a body, the body will move (rotation is a possibility too).. notice the wording.
Yes sir ..ive given the example of couple of torques earlier.
The final thing is :
When the bomb explodes : no external force is there ..hence the COM of bomb rermains at rest .
As for the KE and/or PE of the smitherines ...the chemical energy is the reason.
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so in da case of time bomb how was da torque applied ?