NTS NAT-IE Physics Syllabus

For a body falling freely from rest, what are its velocity and distance after time t (ignoring air resistance)?

Velocity v = gt; distance fallen s = ½gt², where g ≈ 9.8 m·s⁻² (or 10 m·s⁻²).

What does the gradient (slope) of a velocity-time graph represent, and what does the area under it represent?

The gradient represents acceleration; the area under the velocity-time graph represents displacement.

At the highest point of a vertically projected object, what is its velocity and acceleration?

Its velocity is zero, but its acceleration is g (≈ 9.8 m·s⁻²) directed downward.

State Newton's First Law of Motion.

A body remains at rest or in uniform motion in a straight line unless acted upon by a net external force (the law of inertia).

State Newton's Second Law of Motion as an equation.

The net force equals the rate of change of momentum; for constant mass, F = ma.

State Newton's Third Law of Motion.

For every action there is an equal and opposite reaction; forces between two bodies are equal in magnitude and opposite in direction.

Define inertia and state what it depends on.

Inertia is the tendency of a body to resist changes in its state of rest or motion; it depends on (is measured by) the body's mass.

What is the difference between mass and weight?

Mass is the amount of matter in a body (scalar, kg, constant); weight is the gravitational force on it (W = mg, vector, newtons, varies with g).

Define linear momentum and give its formula and SI unit.

Momentum is the product of mass and velocity, p = mv. Its SI unit is kg·m·s⁻¹ (or N·s).

Define impulse and state how it relates to momentum.

Impulse is the product of force and the time it acts, J = F·t. Impulse equals the change in momentum: F·t = Δp = mv − mu.

State the law of conservation of linear momentum.

In the absence of external forces, the total momentum of a system remains constant before and after a collision or interaction.

What is the difference between an elastic and an inelastic collision?

In an elastic collision both momentum and kinetic energy are conserved; in an inelastic collision momentum is conserved but kinetic energy is not (some is converted to other forms).

Write the momentum-conservation equation for two bodies colliding (masses m₁, m₂).

m₁u₁ + m₂u₂ = m₁v₁ + m₂v₂, where u are initial and v are final velocities.

Define work done by a force and give its formula and SI unit.

Work is the product of force and displacement in the direction of the force: W = F·s·cos θ. SI unit is the joule (J).

When is the work done by a force zero?

When there is no displacement, or when the force is perpendicular to the displacement (θ = 90°, so cos θ = 0).

State the formula for kinetic energy.

KE = ½mv², where m is mass and v is speed.

State the formula for gravitational potential energy near Earth's surface.

PE = mgh, where m is mass, g is gravitational acceleration, and h is height above the reference level.

State the work-energy theorem.

The net work done on a body equals the change in its kinetic energy: W_net = ½mv² − ½mu².

State the law of conservation of energy.

Energy can neither be created nor destroyed, only transformed from one form to another; the total energy of an isolated system remains constant.

For a body falling freely, how does the sum of KE and PE behave (ignoring air resistance)?

It remains constant; PE lost equals KE gained, so total mechanical energy is conserved.

Define power and give its formula and SI unit.

Power is the rate of doing work or transferring energy: P = W/t. SI unit is the watt (W = J·s⁻¹).

Express power in terms of force and velocity.

P = F·v, where F is the force in the direction of motion and v is velocity.

Define efficiency and give its formula.

Efficiency is the ratio of useful output energy (or power) to total input energy (or power): Efficiency = (useful output / total input) × 100%.

Why is the efficiency of a real machine always less than 100%?

Because some input energy is always lost to surroundings as wasted forms such as heat (due to friction), sound, or light.

Define angular displacement and angular velocity, with the SI unit of each.

Angular displacement is the angle swept, measured in radians (rad). Angular velocity ω is the rate of change of angular displacement, measured in rad·s⁻¹.

State the relationship between linear speed v and angular velocity ω.

v = rω, where r is the radius of the circular path.

Define centripetal acceleration and give its formula.

Centripetal acceleration is the acceleration directed toward the centre of a circular path: a = v²/r = rω².

What is centripetal force, its direction, and its formula?

Centripetal force is the net force keeping a body in circular motion, directed toward the centre: F = mv²/r = mrω².

Define torque (moment of a force) and give its formula and SI unit.

Torque is the turning effect of a force: τ = F·r·sin θ (force × perpendicular distance from the axis). SI unit is the newton-metre (N·m).

Define moment of inertia and state its rotational analogy.

Moment of inertia (I) is a body's resistance to angular acceleration, depending on mass and its distribution about the axis (I = Σmr²). It is the rotational analogue of mass, and τ = Iα.