We can use the formula for gravitational potential energy (GPE) to find the height at which Jessie is off the ground:
GPE = mgh
where m is the mass of the object (in kg), g is the acceleration due to gravity (9.8 m/s² on Earth), h is the height (in meters) above some reference point where the GPE is defined.
In this case, we know that Jessie has a mass of 50 kg and 4,900 joules of GPE. Plugging these values into the formula, we get:
4900 = (50 kg)(9.8 m/s²)(h)
Solving for h, we get:
h = 4900 J / (50 kg x 9.8 m/s²)
h = 10 meters
Therefore, Jessie is 10 meters off the ground at the point where she has 4,900 joules of GPE.