Applied Physics Chapter 2 - Force & Motion

Study Notes

Objects remain in a state of rest or uniform motion unless acted upon by an external force.
A body experiences zero acceleration if the net external force is zero.
In interstellar space, a spaceship with no external forces continues in uniform motion.
On Earth, when an object is at rest or moving uniformly, external forces acting on it cancel out to yield zero net external force.
Example: A book on a table experiences gravitational force downward and a normal force upward; both forces equalize to maintain a state of rest.

Gravitational Force:
- Mutual attraction between masses, experienced universally.
- Governs motions such as planetary orbits and falling objects.
Electromagnetic Force:
- Acts between charged particles.
- Comprised of electric and magnetic forces; effects occur at both fixed and moving charge levels.
- More potent than gravitational force; governs atomic and molecular structures.
Strong Nuclear Force:
- Binds protons and neutrons within atomic nuclei.
- Offers stability against electrostatic repulsion among protons.
Weak Nuclear Force:
- Operates at a nuclear scale, primarily involved in radioactive decay and other subatomic processes.

No net external force results in either an object being at rest or moving at constant velocity.
Example: A car that accelerates requires an external force, typically friction, while a car moving with constant speed experiences no net external force.

Example Problem 1: Calculating average resistive force exerted on a bullet stopped in a wooden block using mass and distance data.
Example Problem 2: Determining retardation of a car that stops from a specific speed over a set distance.