How is the force of gravity calculated?

The force of gravity acting on an object is calculated using the mass of the object multiplied by the acceleration due to gravity, which is approximately 9.81 m/s² on the surface of the Earth. This formula arises from Newton's second law of motion, which states that force is equal to mass times acceleration. In this context, the acceleration refers specifically to the gravitational acceleration that pulls objects toward the Earth.

The value of 9.81 m/s² is a constant that represents how quickly an object accelerates downward when in free fall near the Earth's surface, due to the gravitational pull. Thus, when calculating the weight of an object, which is a measure of the force of gravity acting on it, one uses the mass of the object (in kilograms) multiplied by this gravitational constant.

Other options don't appropriately describe the calculation of gravitational force. For example, mass multiplied by acceleration could refer to any type of acceleration, not specifically gravitational acceleration. Similarly, mass multiplied by velocity does not relate to force but rather to momentum. Mass divided by area does not pertain to force calculations in this context. Thus, option A accurately reflects the correct calculation of the force of gravity.