AP Physics 1 Dynamics (Forces and Newton’s Laws) Review

Recent questions

• What is static friction?

  Static friction is the force that opposes the initiation of motion between two surfaces in contact. It acts when an external force is applied to an object at rest, preventing it from moving until the applied force exceeds a certain threshold. This threshold is determined by the maximum static friction, which is calculated as the product of the coefficient of static friction and the normal force acting on the object. Once the applied force surpasses this maximum value, the object will begin to move, transitioning from static friction to kinetic friction, which is generally lower than static friction.

• How does Newton's first law work?

  Newton's first law, also known as the law of inertia, states that an object will remain at rest or continue to move at a constant velocity unless acted upon by a net external force. This principle highlights the natural tendency of objects to resist changes in their state of motion. For example, if a box is sliding on a smooth surface without any external forces acting on it, it will continue to slide indefinitely at the same speed and in the same direction. This law is fundamental in understanding motion and is crucial for analyzing scenarios in physics where forces are balanced or unbalanced.

• What is dynamic equilibrium?

  Dynamic equilibrium refers to a state in which an object is moving at a constant velocity, and the net external forces acting on it are balanced, resulting in no acceleration. In this condition, the forces acting on the object, such as gravitational and normal forces, are equal in magnitude and opposite in direction, leading to a net force of zero. This concept is essential in physics as it helps explain how objects can maintain steady motion without changing speed or direction, illustrating the principles of Newton's first law in practical scenarios.

• How do you calculate acceleration?

  To calculate acceleration, you can use Newton's second law of motion, which states that acceleration is equal to the net force acting on an object divided by its mass. The formula can be expressed as a = F_net / m, where 'a' is acceleration, 'F_net' is the total net force, and 'm' is the mass of the object. This calculation is crucial in understanding how forces influence the motion of objects. For example, if a system consists of multiple masses, you must consider the combined effects of all forces acting on the system to determine the overall acceleration accurately.

• What are action-reaction pairs?

  Action-reaction pairs are a fundamental concept in Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. This means that when one object exerts a force on a second object, the second object exerts a force of equal magnitude but in the opposite direction on the first object. These forces act on different objects, which is a key aspect of identifying them as action-reaction pairs. For instance, when a person pushes against a wall, the wall pushes back with an equal force, demonstrating this principle in action. Understanding these pairs is essential for analyzing interactions between objects in various physical scenarios.