Question

7.2 kg object has 95 J of potential energy after being lifted vertically from the floor. How high above the floor is the object? Include a sketch showing the starting position and final position of the object. 

 

Answer 1

Let's denote the final height as $h$. By definition, the potential energy is:

$$E = mgh$$

where $m = 7.2kg$ is the mass of the object, and $g = 9.8N/kg$ is the gravitational acceleration. Expressing $h$ and substituting $E = 95J$, obtain:

$$h = \dfrac{E}{mg}\\ h = \dfrac{95J}{7.2kg\cdot 9.8N/kg} \approx 1.3 m$$

Answer. 1.3 m.