physics prac

Density

Describes how mass is distributed within a given volume. Density (ρ) is defined as mass (m) divided by volume (V), and the equation is ρ = m/V.

Archimedes' principle and buoyancy

Archimedes' principle states that an object immersed in a fluid experiences an upward buoyant force equal to the weight of the fluid displaced by the object.

Average density

Calculated by dividing the total mass of an object by its total volume.

Fundamental units in the SI system

Meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), mole (mol), candela (cd).

Fundamental vs. derived units

Fundamental units are independent and cannot be expressed in terms of other units. Derived units are formed by combining fundamental units.

**Define** temperature and state its unit(s)

Definition: A measure of the degree of hotness or coldness of a body or environment.

Unit(s): Celsius (°C), Fahrenheit (°F), and Kelvin (K).

Temperature during melting or boiling

The temperature remains constant during these phase changes because the added heat is used to overcome intermolecular forces rather than increasing the kinetic energy of the particles.

**Define** energy (and work) and state its unit

Energy is the ability of a system to do work. Work is done when a force is applied to an object and it moves in the direction of the force. Unit: Joule (J).

Heat as thermal energy transfer

Thermal energy vs. temperature:Heat is the transfer of thermal energy between objects due to a temperature difference.

Thermal energy vs. temperature

Thermal energy is the total energy of particles in a substance, while temperature is the average kinetic energy of the particles.

Thermal energy transfer methods

Conduction (direct contact), convection (through fluid motion), and radiation (electromagnetic waves).

Equation of heat flow in conduction

Q = kAΔT/d, where Q is the amount of heat transferred, k is the thermal conductivity, A is the cross-sectional area, ΔT is the temperature difference, and d is the thickness.

Rates of thermal energy transfer

Different substances have different thermal conductivities, affecting the rate of heat transfer.

Evaporation vs. boiling

Evaporation occurs at the surface, while boiling occurs throughout the bulk of a liquid.

Cooling effect of evaporation

Evaporation absorbs energy from the surrounding environment, causing a cooling effect.

Specific heat capacity

The amount of heat required to raise the temperature of a substance by 1 degree Celsius. Unit: J/(kg·°C).

Determining specific heat capacity

Experimental measurements using the equation Q = mcΔT, where Q is the heat transferred, m is the mass, c is the specific heat capacity, and ΔT is the temperature change.

Thermal radiation and temperature/area relationship

The amount of thermal radiation emitted by a surface increases with temperature and surface area.

Factors affecting liquid evaporation rate

Temperature, surface area, and presence of a breeze affect the rate of evaporation.

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* Effective heat insulation methods

Using materials with low thermal conductivity, such as insulation foam or double-glazed windows.

Effects of extreme temperature on the human body

Hypothermia (excessive cooling) and hyperthermia (excessive heating) can have detrimental effects on the body.

Travelling waves and energy transfer

Travelling waves carry energy from one point to another.

Transverse and longitudinal waves

Transverse waves have oscillations perpendicular to the direction of propagation, while longitudinal waves have oscillations parallel to the direction of propagation.

**Define** the terms displacement, amplitude, frequency, period, wavelength and wave speed

Displacement: Distance and direction of an object from its equilibrium position in a wave.

Amplitude: Maximum extent of displacement or the maximum distance a wave moves from its equilibrium position.

Frequency: Number of complete cycles or oscillations of a wave per second.

Period: Time taken for one complete cycle or oscillation of a wave.

Wavelength: Distance between two corresponding points on a wave (e.g., crest to crest or trough to trough).

Wave speed: Speed at which a wave propagates through a medium.

**Describe** the terms crest and trough (in transverse waves), compression and rarefaction (in longitudinal waves)

Crest: Highest point of a wave; Trough: Lowest point of a wave. Compression: Region of high pressure in a longitudinal wave; Rarefaction: Region of low pressure in a longitudinal wave.

Wave speed equation

The general equation for wave speed is v = d/t, where v is the wave speed, d is the distance traveled by the wave, and t is the time taken.

Relationship between wave speed, wavelength, and frequency

The equation v = fλ relates wave speed (v), frequency (f), and wavelength (λ).

Relationship between frequency and period

Frequency (f) is the reciprocal of the period (T), expressed as f = 1/T.

Features of electromagnetic waves

Electromagnetic waves include various forms of light, such as radio waves, microwaves, infrared, visible light, etc. They differ in terms of wavelength, frequency, and energy.

Reflection and transmission of waves at boundaries

When a wave encounters a boundary between two media, it can be reflected (bounced back) or transmitted (pass through) based on factors such as angle of incidence, angle of reflection, and properties of the media.

Refraction of waves

Refraction occurs when a wave changes direction as it passes from one medium to another, due to a change in wave speed.

Diffraction of waves

Diffraction is the bending and spreading of waves as they pass through an opening or encounter an obstacle. It is more pronounced for waves with longer wavelengths.

Principle of superposition

When two or more waves meet, their displacements combine according to the principle of superposition, resulting in constructive or destructive interference.

Interference patterns

Interference occurs when two waves superpose and create regions of constructive and destructive interference, leading to the formation of interference patterns.

Doppler effect

The Doppler effect is the change in frequency or wavelength of a wave as observed by an observer moving relative to the source of the wave. It explains phenomena such as the change in pitch of a siren as a vehicle approaches or moves away.