Figure 1 shows a diagram of a bead on a curved wire, showing its elevated starting position (Point A) and its lower position (Point B).

To calculate the loss of gravitational potential energy, a student needs to measure the change in vertical height, Δh\Delta hΔh, of the bead.
Draw a vertical ruler on Figure 1, placed in a position to measure the change in vertical height, Δh\Delta hΔh, between Point A and Point B of the bead.