Newtonian Mechanics and Forces

Newton's three laws of motion describe the relationship between forces and motion (1st: inertia, 2nd: F=ma, 3rd: action-reaction). Newton's law of universal gravitation is a separate theory about gravitational attraction between masses, not part of the three laws of motion.

Newton's first law states that an object remains at rest or in uniform motion unless acted upon by an external force. The question incorrectly phrases it as 'force, inertia must act' - inertia is the property that resists change in motion, not something that acts. The correct concept is that force causes change in motion.

In curved races (200m and 400m), runners experience centrifugal force which pushes them outward. Middle and outer lanes have less centrifugal force effect compared to inner lanes, making them preferred for maintaining better balance and speed through curves.

The newton, the SI unit of force, is named after Isaac Newton, the English physicist and mathematician who formulated the laws of motion and universal gravitation. His work laid the foundation for classical mechanics.

Newton's first law states that an object at rest stays at rest AND an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force. A moving body with no net force will continue moving at constant velocity, not come to rest.

Friction is a non-conservative force because the work done against friction depends on the path taken - a longer path means more work is lost to friction. In contrast, conservative forces like gravity and electric force have work done that is independent of the path, depending only on initial and final positions.

Nuclear force (strong nuclear force) operates only at extremely short ranges within the atomic nucleus, about 1-3 femtometers. In contrast, electrostatic, magnetic, and gravitational forces are all long-range forces that can act over infinite distances, with their strength decreasing according to the inverse square law.

When walking, the frictional force acts in the forward direction on the foot that is in contact with the ground. Your back foot pushes backward against the ground, and by Newton's third law, friction pushes forward on that foot, propelling you forward. Without this forward friction, walking would be impossible as your foot would just slip backward.

Speed is defined as distance traveled per unit time (s = d/t), measuring how quickly an object moves. Velocity includes direction as well, force causes acceleration, and energy is the capacity to do work. Speed specifically answers 'how fast' without regard to direction.

Bernoulli's principle explains wing lift: the airfoil shape creates faster airflow over the curved upper surface, reducing pressure there relative to the higher pressure below, generating lift. While Newton's 3rd law also applies (action-reaction with downwash), Bernoulli's principle is the standard answer for the primary lift mechanism. D'Alembert's paradox relates to fluid dynamics drag, and Boyle's law concerns gas pressure-volume relationships.

Temperature rises (goes up) and falls (goes down) over time, but temperature itself is a measurement at a location - it doesn't move spatially like a ball, bird, or flight would.

Temperature is a measurement that fluctuates (goes up and down) based on environmental conditions, but it does not physically move from one location to another like a ball, bird, or flight.

Le Chatelier's principle states that when a system at equilibrium is disturbed, it shifts to counteract the disturbance and establish a new equilibrium. It applies to chemical equilibria, not specifically to gases, dispersion forces, or attractive forces (though it can affect systems involving these).

When the bus suddenly accelerates forward, our bodies tend to maintain their state of rest (Newton's first law). This inertia causes us to lean backward relative to the now-moving bus.