Astronomy Practice Exam 2025 – All-in-One Guide to Master Your Astronomy Test!

The force acting upon an object is referred to as weight. Weight is the gravitational force exerted on an object by a celestial body, such as Earth, and is calculated as the product of an object's mass and the acceleration due to gravity. This relationship is defined by Newton's second law of motion, which states that force equals mass times acceleration (F = ma).

In the context of weight specifically, the force due to gravity acting on an object's mass near the Earth's surface is commonly approximated as 9.8 meters per second squared (m/s²). Consequently, an object's weight will vary depending on its mass and the local gravitational field strength, which is why weight is different on different planets.

Mass refers to the amount of matter in an object and is a scalar quantity, meaning it does not change regardless of location. Momentum is the product of an object's mass and its velocity, describing its motion rather than the forces acting upon it. Friction is a specific type of force that resists the relative motion of solid surfaces, fluid layers, and material elements sliding against each other, but it is not synonymous with the total force acting on an object.