Newtonian Mechanics and Forces

Gravity is the force of attraction between any two objects that have mass. It's one of the four fundamental forces of nature. Force is a push or pull, acceleration is rate of velocity change, and work is force times distance.

Air resistance is the force that opposes the motion of objects through air. It's caused by air particles colliding with the moving object, creating drag that slows it down. This force increases with speed and surface area.

According to Newton's Second Law of Motion, force is what can change the motion of an object. The law states that F=ma, meaning force equals mass times acceleration. Velocity, mass, and speed are properties of the object itself, not external agents that change motion.

Impulse is the product of force and the time interval during which the force acts (J = F × Δt). Momentum is mass times velocity (p = mv), while acceleration is force divided by mass (a = F/m).

Electromagnetic radiation is energy that travels through space in waves. This includes visible light, radio waves, X-rays, and other forms of radiation. Inertia is resistance to motion, potential energy is stored energy, and kinetic energy is energy of motion - none of these describe energy moving in waves.

When a spring is compressed or stretched, it exerts a force that tries to bring it back to its original length. This restoring force is proportional to the displacement (Hooke's Law). Potential and gravitational forces are different physical concepts, and spring force is what creates the restoring effect.

Force is defined as the rate of change of momentum (dp/dt), which is Newton's actual second law. F = ma is derived from this when mass is constant. Rate of change of acceleration would be jerk (da/dt), and rate of change of velocity is acceleration, not force. Mass * acceleration is a consequence, not the definition.

The equation of continuity in fluid dynamics is based on the principle of conservation of mass. It states that the mass flow rate of a fluid remains constant through a streamline, meaning fluid cannot be created or destroyed within the flow. This fundamental principle applies to incompressible fluids and is essential for understanding fluid mechanics in pipes, channels, and various engineering applications.

When the paper is jerked quickly, the force is applied for too short a time to overcome the book's inertia, so the book tends to stay where it is. Inertia is the tendency of a massive object to resist changes to its state of motion. Gravity (A) and action-reaction (C) are real but do not explain the quick-pull effect.

The statement is false. When a bus moves at constant velocity, the penny would return to your hand due to inertia. However, if the bus accelerates or decelerates, the penny would NOT return to your hand because of inertia - it would continue at the original velocity while you and the bus change velocity. The penny's motion depends on whether the bus maintains constant velocity or accelerates.

In space, there is no air resistance or friction to slow down the wrench. According to Newton's first law of motion (law of inertia), an object in motion stays in motion at constant velocity unless acted upon by an external force. Once thrown, no force is needed to keep it moving - it will continue indefinitely at the same velocity.

Inertia is the tendency of objects to maintain their state of motion. This property is quantified by mass - mass is a measure of an object's resistance to changes in its motion. Objects with more mass have more inertia.

For an object moving in a straight line at constant speed, both the magnitude and direction of velocity remain unchanged. Acceleration is the rate of change of velocity, so zero change means zero acceleration.