Newtonian Mechanics and Forces

Jet engines work on Newton's third law (action-reaction) which is based on conservation of linear momentum. The engine expels mass (high-velocity exhaust gases) backward, generating forward thrust. This is fundamentally about linear momentum change.

According to Newton's third law, when the horse pushes backward against the ground, the ground exerts an equal and opposite forward force on the horse. This reaction force is what actually propels the horse forward.

When the bus stops suddenly, passengers continue moving forward due to inertia of motion - the tendency of moving objects to remain in motion. No force pushes them from behind; rather, their bodies maintain their state of motion while the bus decelerates. This is Newton's first law.

Rocket propulsion works on Newton's third law and conservation of momentum. As rocket engine expels gases backward at high velocity, the rocket gains equal forward momentum. This momentum exchange allows rockets to work even in vacuum where there's nothing to push against.

Mass is a scalar quantity because it only has magnitude and no direction. Force, acceleration, and weight are all vector quantities as they have both magnitude and direction - weight always points toward Earth's center, force acts in the direction of application, and acceleration follows the direction of the net force.

Correct. The option removes the error of pronoun ambiguity by referring to 'pendulum' and not its swing as coming back to equilibrium.

Oscillatory motion is defined as repetitive back-and-forth movement around a central point or equilibrium position. Option A correctly identifies this as 'Back and Forth'. The other options describe different types of motion: circular (B), uniform (C), and non-uniform (D).

Vibratory motion is defined as to-and-fro motion about a mean position. Examples include the motion of a pendulum, a vibrating string, or molecules in a sound wave.

Rolling friction occurs when a rounded object (like a ball or wheel) rolls over a surface instead of sliding across it. The contact point continuously changes, creating less resistance than sliding friction.

Rolling objects need friction between wheel and surface to grip (otherwise they'd just spin in place). Writing requires friction between pen/paper to leave marks. Walking requires friction between feet and ground to push forward without slipping. All depend on friction.

Throwing sand on snow-covered tracks increases surface roughness, which increases friction between wheels/feet and the track. This provides better traction on otherwise slippery surfaces. The other options (polishing, greasing, oiling) all decrease friction.

Of the three types of friction listed, rolling friction offers the least resistance to motion. This is why wheels are so efficient - they convert high-resistance sliding friction into low-resistance rolling friction.

The wheel reduces friction by converting sliding friction into rolling friction. This fundamental principle transformed transportation, allowing heavy loads to be moved with much less effort. The wheel doesn't eliminate or generate energy - it reduces wasteful friction.

Drag is the frictional force exerted by fluids (both liquids AND gases) on objects moving through them. Air resistance (gas) and water resistance (liquid) are both forms of drag that oppose motion through the fluid.

Objects lose kinetic energy when moving through fluids due to fluid friction (drag) that opposes their motion. Static, sliding, and rolling friction occur between solid surfaces in contact, not in fluids like air or water.