Question

An object with a mass of 12 g sitting on a ledge 15 m above the ground starts to fall. What was the potential energy of the object before it fell?

a. 1.8 J
b. 2.7 J
c. 3.6 J
d. 4.5 J

Answer 1

The potential energy of a 12g object sitting 15m above the ground is 1.8 J, calculated using the gravitational potential energy formula PE = mgh.

Step-by-step explanation:

To determine the potential energy of an object before it falls, we use the formula for gravitational potential energy (PE) which is PE = mgh, where m is the mass of the object, g is the acceleration due to gravity (9.8 m/s²), and h is the height above the reference point.

In this case, the object has a mass of 12 g (which is 0.012 kg in SI units), and it is sitting at a height of 15 m above the ground. Therefore, the potential energy before it fell is:

PE = (0.012 kg)(9.8 m/s²)(15 m) = 1.764 J, which rounds to 1.8 J.

The correct answer to the student's question, "What was the potential energy of the object before it fell?", is a. 1.8 J.