Change in potential energy on a roller coaster drop (frictionless)

AI Thread Summary
The discussion focuses on calculating the gravitational potential energy of an 800 kg roller coaster as it moves from point A to point B, with point B set as the zero level for potential energy. The initial calculation for potential energy at point A was based on the formula Ug = mgh, using the vertical component of the height. However, a mistake was identified in the vertical drop calculation, indicating that the height used was incorrect. The correct height should be 38.1 m, not 44.1 m, which affects the potential energy calculation. Accurate calculations are essential for determining the change in potential energy during the coaster's drop.
closer
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800 kg roller coaster is initially at the top of a rise, at point A. It then moves 125 ft (38.1 m), at an angle of 40.0° below the horizontal, to a lower point, B.

(a) Choose point B to be the zero level for gravitational potential energy. Find the potential energy of the roller coaster-Earth system at points A and B and the change in potential energy as the coaster moves.

To start, I aimed to find the potential energy at point A:
Ug = mgh
Ug = (800)(9.8)(y component of h)
Ug = (800)(9.8)(38.1sin40)
Ug = 222561.92 J

What am I missing in my process? Thanks in advance.
 
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Everything looks good except your final answer. Redo that calculation.
 
closer said:
800 kg roller coaster is initially at the top of a rise, at point A. It then moves 125 ft (38.1 m), at an angle of 40.0° below the horizontal, to a lower point, B.

(a) Choose point B to be the zero level for gravitational potential energy. Find the potential energy of the roller coaster-Earth system at points A and B and the change in potential energy as the coaster moves.

To start, I aimed to find the potential energy at point A:
Ug = mgh
Ug = (800)(9.8)(y component of h)
Ug = (800)(9.8)(38.1sin40)
Ug = 222561.92 J

What am I missing in my process? Thanks in advance.

I think your vertical drop calculation is in error. Your answer suggests the original height was 44.1m when the problem says it was 38.1m
 
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