A 2.2 kg rock rests on the edge of a bridge that is 3.3 m above a river.What is the gravitationa l potential energy of the rock when measured from the surface of the river? What is the gravitationa potential energy when measured from the edge of the bridge?

Here's how to calculate the gravitational potential energy (GPE) of the rock:<br /><br />**Understanding Gravitational Potential Energy**<br /><br />GPE is the energy an object possesses due to its position in a gravitational field. It's calculated using the formula:<br /><br />GPE = mgh<br /><br />Where:<br /><br />* m = mass (in kg)<br />* g = acceleration due to gravity (approximately 9.8 m/s² on Earth)<br />* h = height (in meters)<br /><br />**Calculations**<br /><br />* **GPE relative to the river:**<br /><br /> * m = 2.2 kg<br /> * g = 9.8 m/s²<br /> * h = 3.3 m<br /><br /> GPE = (2.2 kg) * (9.8 m/s²) * (3.3 m) = 71.274 J (approximately 71.3 J)<br /><br />* **GPE relative to the bridge:**<br /><br /> * m = 2.2 kg<br /> * g = 9.8 m/s²<br /> * h = 0 m (since the height is measured from the bridge itself)<br /><br /> GPE = (2.2 kg) * (9.8 m/s²) * (0 m) = 0 J<br /><br />**Explanation**<br /><br />The GPE of the rock relative to the river is 71.3 J. This means it has the *potential* to do 71.3 J of work as it falls to the river.<br /><br />The GPE of the rock relative to the bridge is 0 J. This makes sense because GPE is about *relative position*. If we're measuring from the bridge itself, the rock has no height and therefore no potential energy to fall further relative to that point.<br />