Newtonian Mechanics and Forces

Momentum is defined as the product of an object's mass and its velocity (p = mv). Force is related to the rate of change of momentum, not its definition. The statement incorrectly substitutes force for mass in the momentum formula.

The pascal (Pa) is the SI unit of pressure, defined as one newton per square metre (N/m²). Newton measures force, joule measures energy or work, and farad measures capacitance (ability to store charge).

Speed is defined as the distance traveled per unit of time. Average speed specifically is total distance divided by total time taken. Work is force times distance, acceleration is rate of change of velocity, and force is mass times acceleration.

Force is a vector quantity because it has both magnitude and direction, as described by Newton's laws. Scalar quantities like length, weight, and time have only magnitude without any directional component. Therefore, force is the correct answer as it is not a scalar.

Lift is the primary force that enables an aircraft to fly and overcome gravity. It is generated by the wings as air flows over them, creating an upward force that counteracts the aircraft's weight. Thrust moves it forward, but lift keeps it airborne.

Force and energy are fundamentally different physical quantities. Force is a push or pull that can cause acceleration (measured in Newtons), while energy is the capacity to do work (measured in Joules). A force can act without energy transfer if there's no displacement in the force's direction.

Energy from motion is kinetic energy, not potential energy. Potential energy depends on an object's position or state in a force field (like gravitational height), while kinetic energy depends on its velocity and mass.

Work is defined as force applied through a displacement (distance). The formula W = F × d requires both a force component in the direction of motion and some displacement. No movement means zero work, regardless of force applied.

Energy is defined as the capacity or ability to do work. This fundamental concept means any object or system possessing energy can potentially exert forces and cause displacement. Different energy forms (kinetic, potential, thermal) all share this capacity to perform work.

Friction is a non-conservative force because the work done by friction depends on the path taken, not just endpoints. Energy is lost as heat during friction, making it irreversible. Conservative forces like gravity are path-independent.

Elasticity is the property of a material to return to its original shape after an applied pressure or force is removed. When deformed within elastic limits, materials recover completely. Plasticity (option A) is the opposite - permanent deformation that remains after load removal.

When a vehicle turns at high speed, the centrifugal force (the apparent outward force in a rotating reference frame) is responsible for accidents or skidding. Centripetal force is the inward force that keeps the vehicle on the curved path.

According to relativity, as an object approaches the speed of light, time dilation occurs - time passes slower for the moving object relative to a stationary observer. The phrasing 'control time constraint' is awkward but refers to this relativistic time effect. Objects don't disappear or lose mass simply by moving at light speed.

Objects float due to buoyant force - an upward force exerted by fluids that opposes the weight of an immersed object. This force is equal to the weight of the fluid displaced by the object (Archimedes' principle). The spelling 'bounacy' is a typo for 'buoyancy'.

Gravity is fundamentally an attractive force that 'pulls' objects toward each other, specifically toward the center of mass. It never pushes - the concept of 'push' gravity contradicts Newton's law of universal gravitation and Einstein's general relativity. All gravitational attraction is a pulling force.