A ladder with a length of 2.8 m and a weight of 5.2 kg is leaned against the wall so that it makes an angle of 60 degrees with the ground. The center of gravity of the ladder is exactly in the middle and is marked with a black dot in the picture. If the ladder lies on the ground, its center of gravity is at a height of 60 mm. Calculate the change in potential energy of the ladder as the ladder slides to the ground.
Ladder
