During one year, 1.25 × 10^18 J of energy was transferred from the National Grid - AQA - GCSE Physics - Question 5 - 2021 - Paper 1

To find the mean energy transferred each second, divide the total energy transferred over the year by the total number of seconds in that year:

$E = \frac{1.25 \times 10^{18} \text{ J}}{3.16 \times 10^7 \text{ s}}$

Calculating this gives:

$E \approx 3.96 \times 10^{10} \text{ J/s}$

Thus, the mean energy transferred each second is approximately 3.96 × 10^10 J.