A student will have to be abnormally careful with language in order to be successful on this sublevel. Language? Yes! Language! Acceleration. Acceleration of gravity, Gravity, Force of gravity. Don't be fooled! All these terms mean something different and if you fail to recognize this fact then you will miss this question and others like it. So here's a language lesson:
The acceleration of gravity is the acceleration value experienced by an object which is under the sole influence of gravity. It might be thought of as the acceleration caused by gravity alone. It's value is the same for all objects regardless of their mass. The acceleration of gravity is such an important value in Physics that it has it's own symbol - g. On Earth, the value at which an object accelerates when under the sole influence of gravity is 9.8 m/s/s.
The acceleration of an object is simply the rate at which its velocity changes. When in free fall, that value of acceleration is 9.8 m/s/s. When not in free fall, the acceleration is likely to be some other value. The acceleration is always the ratio of net force to mass, whether in free fall or not in free fall.
The force of gravity is the pull which is exerted upon an object by the Earth (or moon or ...). It is a downward pull which any object with mass (thus, any object) will experience. The force of gravity is sometimes referred to as the object's weight. It's value is dependent upon the mass of the object. More details about the gravity force will be discussed in a later unit.
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