Gravitational potential energy
Work, Energy & Power - OCR A-Level Physics
Key Definition
Gravitational potential energy
The energy an object possesses due to its position in a gravitational field. Near the Earth's surface, the change in GPE depends on the vertical height change.
The energy an object possesses due to its position in a gravitational field. Near the Earth's surface, the change in GPE depends on the vertical height change.
$$E_p = mgh$$
$$\Delta E_p = mg\Delta h$$
- This equation applies near the Earth's surface where g is approximately constant
- Only the vertical change in height matters, not the path taken or the distance along a slope
- The reference point ($h = 0) can be chosen$ for convenience
- On a slope: $\Delta$h = $s\sin\theta$, where s is the distance along the slope $and \theta$is the angle of incline
Common Mistake
MEDIUM
Students often: On inclined plane problems, students use the distance along the slope instead of the vertical height change.
Instead: Make sure to always use the vertical height: Delta $h = s \sin(\theta)$, where s is the distance along the slope and theta is the angle of the incline to the horizontal.
Instead: Make sure to always use the vertical height: Delta $h = s \sin(\theta)$, where s is the distance along the slope and theta is the angle of the incline to the horizontal.