Answer:
g = 9.8 [m/s²]
Step-by-step explanation:
To solve this problem we must remember that the potential energy is defined as the product of mass by gravitational acceleration by the height or elevation with respect to a reference level.
Ep = m*g*h
where:
Ep = potential energy = 235.2 [J]
m = mass of the book = 6 [kg]
g = gravity acceleration [m/s²]
h = elevation = 4 [m]
Now replacing these values:
235.2 = 6*g*4
g = 235.2/(24)
g = 9.8 [m/s²]