I only need help on the last question about gravity. Nevermind. I got confused w
ID: 779249 • Letter: I
Question
I only need help on the last question about gravity.
Nevermind. I got confused with it in the notes the professor gave with another question. I thought that he somehow found an answer for the last question through a free body diagram. It was a different question.
o A 500g book slides up a ramp that is 1.00 m long and inclined at 30.0 degrees. 30° o How much work is done by gravity? How much work is done by gravity when the book slides back to its original position? What is the total work done by gravity? Is gravity a conservative force?Explanation / Answer
Any force with the property that work done in moving any particle/object from one position to other doesn’t depend upon the path taken but only on the initial and final positions of the object is called conservative force. It means that if a object moves along a circular path and reaches back to its initial position then total work done is zero.
Informally the force which conserves mechanical energy is called conservative force.
Now taking the example of Gravitational Force. Suppose we throw a object of mass ‘m’ upward suppose it goes up to a height h.
then the work done in throwing object in upward direction w1 = -mgh (use ‘-g’ sign convention )
and the work done while returning to the same path w2 = mgh
total work done W = w1 + w2 = -mgh+mgh = 0
Hence, total energy loss will also be zero in this case.
So, Gravitational Force is Conservative Force.
It won’t be the same case if any friction is present, there will be some mechanical energy loss due to friction.
Therefore, friction is a non-conservative force.