I'm working on a lab experiment using https://phet.colorado.edu/en/simulation/the-ramp the ramp. Using a piano with the ramp angle set to 10 degrees, I'm supposed to test the work-energy theorem by letting the piano roll down the slope with no friction and record the values of work and energy. Based on what I know, I thought under these circumstances, the total mechanical energy of the piano should remain the same as it slides down. It would just convert from potential energy to kinetic energy; however, this is not the observed case and I can't explain why. Uploaded is the spreadsheet where I recorded my results.

H Object Piano Applied F 0 Mass 225 kg Ramp Angle 10 0.4 Starting P 15 h 2.6 m 1,000 750 Fapplied =0.00 N 500 Ffriction =0.00 N Time position F_applied F_friction F_gravity F_wall Total E Thermal E Potential Kinetic E W_applierW_friction W_gravity W_sum 250 0.68 -0.11 15 0 0 -382.89 0 5744.86 0 5743.41 1.45 5744.86 0 -5743.41 1.45 1.01 -0.68 14.85 0 -382.89 0 5738.11 0 5685.98 52.13 5738.11 0 -5685.98 52.13 Parallel Force (Newtons) 2 OO 1.22 -1.08 14.64 0 -382.89 0 5736.25 0 5605.57 130.68 5736.25 0 -5605.57 130.68 250 1.51 -1.53 14.28 O 0 -382.89 0 5731.62 0 5467.73 263.89 5731.62 0 -5467.73 263.89 500 1.72 -1.93 13.88 0 0 -382.89 0 5733.04 0 5314.57 418.47 5733.04 0 -5314.57 418.47 -750 1.89 -2.21 13.53 0 -382.89 0 5731.15 0 5180.56 550.59 5731.15 0 -5180.56 550.59 1.000 2.02 -2.44 13.21 0 -382.89 0 5727.36 0 5058.03 669.33 5727.36 0 -5058.03 669.33 30,000 Total =5781.75 J 2.27 -2.84 12.59 0 -382.89 0 5725.63 0 4820.64 904.99 5725.63 0 -4820.64 904.99 20,000 Thermal -5781.75 J 2.6 -3.4 11.54 0 -382.89 0 5721.78 0 4418.6 1303.18 5721.78 0 -4418.6 1303.18 2.81 -3.74 10.82 0 -382.89 0 5719.77 4142.92 1576.85 5719.77 0 -4142.92 1576.85 10,000 2.96 -4.03 10.17 0 -382.89 0 5718.85 0 3894.03 1824.82 5718.82 0 -3894.03 1824.82 Energy (Joules) 2 3.11 -4.28 9.55 0 -382.89 0 5713.55 0 3656.64 2056.91 5713.55 0 -3656.64 2056.91 3.29 -4.62 8.66 0 -382.89 0 5713.25 3315.86 2397.39 5713.25 0 -3315.56 2397.39 - 10,000 3.48 -4.9 7.86 0 -382.89 0 5710.58 0 3009.55 2701.03 5710.58 0 -3009.55 2701.03 -20,000 3.63 -5.18 7.01 0 -382.89 0 5706.86 0 2684.09 3022.77 5706.86 o -2684.09 3022.77 3.75 -5.35 6.48 0 -382.89 0 5705.66 0 2481.15 3224.5 5705.66 0 -2481.15 3224.5 -30.000 20,000 3.88 -5.58 5.75 0 -382.89 0 5705.26 0 2201.64 3503.61 5705.26 0 -2201.64 3503.61 1910.64 15,000 applied "5781.75 J -5.81 4.99 0 -382.89 0 5704.95 3794.31 5704.95 0 -1910.64 3794.31 -382.89 0 5700.92 1604.33 4096.59 5700.92 0 -1604.33 4096.59 10,000 Friction " -5781.75 J 4.15 -6.03 4.19 1.55 -6.75 1.64 -382.89 0 5700.88 0 627.95 5072.93 5700.88 -627.95 5072.93 5,000 4.68 -6.94 0.72 0 -382.89 0 5697.23 0 275.68 5421.55 5697.23 0 -275.68 5421.55 Work (Joules) 2 6 4.8 -7.17 -0.23 0 5781.75 0 5781.75 5781.75 0 0 5781.75 5,000 O O 0 5781.75 O 4.93 -7.17 -1.19 5781.75 5781.75 0 5781.75 - 10,000 OOO 5.12 -7.17 -2.63 0 5781.75 0 0 5781.75 5781.75 0 0 5781.75 - 15,000 5.62 0 -6 0 48390.17 5781.75 5781.75 0 5781.75 -5781.75 0 -20,000