In Newtonian mechanics, how is the net force on an object defined?

• A. The product of the object’s mass and its velocity
• B. The vector sum of all external forces acting on the object
• C. The force the object exerts on its surroundings (the reaction force)
• D. The sum of the magnitudes of all forces acting on the object, ignoring direction

Answer: (B)

Verified step by step guidance

1. Recall that in Newtonian mechanics, force is a vector quantity, meaning it has both magnitude and direction.
2. Understand that the net force on an object is the combined effect of all external forces acting on it, taking into account their directions.
3. Express the net force mathematically as the vector sum of all individual external forces: \(\\vec{F}_{net} = \\sum \\vec{F}_i\).
4. Recognize that this net force determines the acceleration of the object according to Newton's second law: \(\\vec{F}_{net} = m \\vec{a}\), where \(m\) is the mass and \(\\vec{a}\) is the acceleration.
5. Note that simply summing magnitudes or considering the force the object exerts on surroundings does not correctly define the net force on the object.