Answer: 3 kg
Step-by-step explanation:
The formula for potential energy is Ug=mgh where Ug is potiental energy, m is mass, g is the acceleration caused by gravity which is either 9.8 m/s^2 or 10m/s^2 depending on your textbook and h is the height and or displacement. So…
120 = m(10)(4)
120=40m
m= 3 kg