Final answer:
The surface's albedo is 64.7%, calculated by using the formula Albedo = (Reflected Energy / Incident Energy) × 100%, with 55 J of the energy being reflected after subtracting the 30 J absorbed from the total 85 J incident energy.
Step-by-step explanation:
The surface’s albedo is a measure of how much sunlight (or energy) that hits the surface is reflected back without being absorbed. To calculate albedo, we use the formula:
Albedo = (Reflected Energy / Incident Energy) × 100%
Given that 85 J of energy shines on the test surface and 30 J of it gets absorbed, the reflected energy is 85 J - 30 J = 55 J.
Substituting the values into the albedo formula:
Albedo = (55 J / 85 J) × 100% = 64.7%
Therefore, the surface’s albedo is 64.7%.