an object thrown at an angle to the ground moves in a curved path and falls back to the ground with the same speed then work done by force of gravity on the object is +ve,-ve or zero

Asked by Akanksha Sood | 12th Jan, 2014, 03:56: PM

Expert Answer:

The work done by force of gravity on the object is zero.
 
The work-energy theorem in classical mechanics says that the change in kinetic energy of a system equals the net work done by external forces on the system. 
The work done by gravity during the upward motion of the projectile cancels the work done during its downward motion. 
 
Secondly the magnitude of the velocity has not changed which implies that the kinetic energy has not changed which implies no work has been done by gravity.

Answered by Komal Parmar | 12th Jan, 2014, 04:41: PM

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