A boulder rests on a ledge 31.2 m above a lake. If it has 2.65 x 10 J of gravitational potential energy relative to the lake surface, what is the mass of the boulder?

This question is incomplete, the gravitational potential energy is 2.65 x 10^5 J

mass of the boulder = 866.7g

Explanation:

Potential energy (P.E) refers to the energy due to the position of a body. It can be calculated as follows:

P.E = m × g × h

Where;

m = mass of substance (g)

g = acceleration due to gravity (m/s²)

h = height (m)

According to the information provided in this question,

h = 31.2 m

g = 9.8m/s²

m = ?

P.E = 2.65 x 10^5 J

Using P.E = m × g × h

2.65 x 10^5 = m × 9.8 × 31.2

2.65 x 10^5 = 305.76m

265000 = 305.76m

m = 265000 ÷ 305.76

m = 866.69

mass of the boulder = 866.7g

1. for the first question, we must find the mass of the anhydrous salt, mgso₄. the molar mass for mgso₄·7h₂o is 246.47 g/mol, while that of mgso₄ is 120.37 g/mol.7.834 g mgso₄·7h₂o * 1 mol mgso₄·7h₂o/246.47 g * 1 mol mgso₄/1 mol mgso₄·7h₂o * 20.37 g mgso₄/mol = 0.647 g mgso₄

2. mass of water = mass of sample - mass of anhydrous salemass of water = 7.834 - 0.647 = 7.19 gpercent water in hydrate = 7.19/7.834 * 100 = 91.74%