Navy Sailor Test Physics Syllabus

Define work in physics, give its formula and SI unit.

Work is done when a force moves a body in the direction of the force: W = F x d (or F d cos(theta)). Its SI unit is the joule (J), where 1 J = 1 N m.

Define energy and state its SI unit.

Energy is the capacity (ability) to do work. Its SI unit is the joule (J).

Write the formula for kinetic energy and define it.

Kinetic energy is the energy possessed by a body due to its motion. KE = 1/2 m v^2, where m = mass and v = speed.

Write the formula for gravitational potential energy and define it.

Gravitational potential energy is the energy a body has due to its position/height. PE = mgh, where m = mass, g = gravity, h = height.

State the law of conservation of energy.

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

Define power, give its formula and SI unit.

Power is the rate of doing work or rate of transfer of energy: P = work / time (P = W/t). Its SI unit is the watt (W), where 1 W = 1 J/s.

What is 1 horsepower (hp) equal to in watts?

1 horsepower (hp) is approximately equal to 746 watts.

Name the three common states of matter and describe the arrangement of particles in each.

Solid: particles closely packed in fixed positions, vibrating. Liquid: particles close but free to move/slide past each other. Gas: particles far apart, moving randomly at high speed.

Compare the three states of matter in terms of shape and volume.

Solid: definite shape and definite volume. Liquid: no definite shape (takes shape of container) but definite volume. Gas: neither definite shape nor definite volume (fills container).

Define density, give its formula and SI unit.

Density is mass per unit volume (density = mass / volume, p = m/V). Its SI unit is kilogram per cubic metre (kg/m^3).

What is the density of water, and why is it important as a reference?

The density of pure water is 1000 kg/m^3 (or 1 g/cm^3). It is used as a reference for relative density and to predict whether objects float or sink.

Define pressure, give its formula and SI unit.

Pressure is the force acting normally (perpendicularly) per unit area: P = F/A. Its SI unit is the pascal (Pa), where 1 Pa = 1 N/m^2.

Write the formula for pressure exerted by a liquid column at a given depth.

Pressure in a liquid P = p g h (rho g h), where p = liquid density, g = gravitational acceleration, h = depth below the surface.

State Pascal's Law (Pascal's Principle).

Pressure applied to an enclosed (confined) fluid is transmitted equally and undiminished in all directions throughout the fluid. It is the basis of the hydraulic press.

State Archimedes' Principle.

When a body is wholly or partially immersed in a fluid, it experiences an upward buoyant force (upthrust) equal to the weight of the fluid it displaces.

What is atmospheric pressure at sea level in pascals and in the common 'standard atmosphere' value?

Atmospheric pressure at sea level is about 101,325 Pa (1.013 x 10^5 Pa), equal to 1 standard atmosphere (atm), supporting a 760 mm column of mercury.

Define elasticity.

Elasticity is the property of a body by which it regains its original shape and size after the deforming force is removed.

State Hooke's Law and give its formula.

Within the elastic limit, the extension (or deformation) of a body is directly proportional to the applied force: F = k x, where k is the spring constant and x is the extension.

What is the elastic limit?

The elastic limit is the maximum stress or force beyond which a body does not return to its original shape after the deforming force is removed (it becomes permanently deformed).

Define stress and strain.

Stress is the force applied per unit cross-sectional area (stress = F/A). Strain is the ratio of change in dimension to original dimension (strain = change in length / original length); strain has no units.

Define temperature and name the three common temperature scales.

Temperature is the measure of the degree of hotness or coldness of a body (average kinetic energy of its particles). The three common scales are Celsius (C), Fahrenheit (F), and Kelvin (K).

What are the freezing and boiling points of water on the Celsius and Kelvin scales?

On Celsius: 0 C (freezing) and 100 C (boiling). On Kelvin: 273 K (freezing) and 373 K (boiling).

Give the conversion formula between Celsius and Kelvin, and between Celsius and Fahrenheit.

K = C + 273. F = (9/5)C + 32 (and C = 5/9 (F - 32)).

Define heat and explain how it differs from temperature.

Heat is a form of energy that flows from a hotter body to a colder body due to a temperature difference (measured in joules). Temperature measures the degree of hotness and determines the direction of heat flow.

Define specific heat capacity and give its formula.

Specific heat capacity is the heat required to raise the temperature of 1 kg of a substance by 1 K (or 1 C). Q = m c (change in T), where c is specific heat capacity; SI unit J/(kg K).

Define latent heat and name its two types.

Latent heat is the heat absorbed or released during a change of state at constant temperature. The two types are latent heat of fusion (solid<->liquid) and latent heat of vaporization (liquid<->gas).

Define thermal expansion and name its three types.

Thermal expansion is the increase in size of a body when heated. The three types are linear expansion (length), superficial/areal expansion (area), and cubical/volume expansion (volume).

What is the anomalous expansion of water?

Between 0 C and 4 C, water contracts instead of expanding on heating, reaching maximum density at 4 C. Below 4 C and on freezing it expands, which is why ice floats and lakes freeze from the top.

Name the three methods of heat transfer and state which require a medium.

Conduction (needs a medium, mainly in solids), convection (needs a fluid medium, in liquids and gases), and radiation (needs no medium, can travel through vacuum).

Define conduction and convection of heat.

Conduction is heat transfer through a material by particle vibration/collision without the particles moving from their positions (mainly in solids). Convection is heat transfer by the actual movement of heated fluid (liquid or gas) carrying energy.

Define radiation as a method of heat transfer and give one property.

Radiation is the transfer of heat as electromagnetic waves (infrared) that require no medium and travel at the speed of light; dark, dull surfaces are good emitters and absorbers while shiny surfaces are poor ones.

Define a wave and distinguish between transverse and longitudinal waves.

A wave is a disturbance that transfers energy from one place to another without transferring matter. In transverse waves the particles vibrate perpendicular to the direction of travel (e.g., light); in longitudinal waves they vibrate parallel to it (e.g., sound).

Define wavelength, frequency, and amplitude of a wave.

Wavelength: distance between two consecutive identical points (e.g., crest to crest). Frequency: number of waves passing a point per second (unit hertz, Hz). Amplitude: maximum displacement of a particle from its rest position.

State the wave equation relating speed, frequency, and wavelength.

Wave speed = frequency x wavelength (v = f x lambda), where v is speed (m/s), f is frequency (Hz), and lambda is wavelength (m).

What type of wave is sound, what medium does it need, and what is its approximate speed in air?

Sound is a longitudinal mechanical wave. It needs a material medium (cannot travel through vacuum). Its speed in air is about 330-340 m/s at room temperature.

What is an echo, and what causes it?

An echo is a sound heard again after reflection from a hard, distant surface. It is caused by the reflection of sound waves back to the listener.