The acceleration due to gravity on Earth's surface, which is denoted by the letter g, is a value that has been experimentally determined and accepted to be approximately 9.81 meters per second squared (m/s^2). This value represents how much the velocity of an object will change each second as it accelerates towards the Earth, if it is falling under the influence of Earth's gravity alone, without any air resistance or other forces acting on it.
When we compare the value of 9.81 m/s^2 to the multiple-choice options provided, we see that it is closest to option c, which states "about 10 m/s^2." Therefore, the correct choice for the value of g on Earth's surface is:
c. about 10 m/s^2