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Let us see whether it is so. I throw a brick up to a mason who is busy building the roof of a temple. He catches it and cements it in the roof. Gravityovercame the propelling energy which started the upward motion of the brick, and the dynamic energy of the ascending brick until it ceased to ascend. At that moment it was caught and fastened to the roof. No natural force could now move it, therefore it possesses no longer potential energy. The motion and the dynamic energy of the ascending brick are absolutely annihilated. Another example from their own text books. You fire a gun upward from the foot of a hill and the ball lodges in a crevice of the rock on that hill.