Physics

• Energy can be transferred between objects by work done, heating or cooling, and electric current.
• Work done = force x distance moved in direction of force
• Energy can be transferred from one object to another by work done or heat transfer.
• Water waves travel along the surface of liquids.
• Ultrasound has frequencies above the range of human hearing (20 Hz - 20 kHz).
• The speed of sound is dependent on temperature and pressure.
• Sound waves are longitudinal waves that require a medium to propagate through.
• Convection involves the movement of heated molecules away from their source, creating convection cells where cooler air sinks and warmer air rises.
• Conduction occurs when particles vibrate more rapidly at higher temperatures, causing them to collide with neighboring particles and transfer kinetic energy through contact.
• The SI unit for energy is joules (J).
• Heat is the energy that flows from hotter to colder objects due to temperature difference.
• Cooling is the reverse process where heat flows out of an object into its surroundings.
• Heating is the transfer of energy from one object to another due to a temperature difference.
• Power is defined as the rate at which energy is used up or produced.
• Work is done when a force moves an object through a distance.
• The law of conservation of energy states that the total amount of energy remains constant during any process.
• Increasing temperature increases the speed of sound.
• The speed of sound is dependent on temperature.
• Sound travels faster through solids than liquids and gases.
• Reflection occurs when light bounces off a smooth surface at an angle equal to its incidence angle.
• Refraction occurs when light changes direction as it passes from one medium into another with different refractive indices.
• In solids, sound travels as transverse waves due to particles vibrating perpendicularly to the wave's direction of motion.
• Infrared radiation is emitted by all objects at temperatures above absolute zero (-273°C) and travels as electromagnetic waves.
• Thermal conductivity refers to how easily energy is conducted through an object.
• In liquids and gases, sound travels as longitudinal waves with particles oscillating parallel to the wave's direction of motion.
• Radiation refers to the emission or absorption of electromagnetic radiation by objects due to changes in their temperature.
• Work done is calculated as force multiplied by distance moved in the direction of the force.
• Heat capacity is defined as the amount of heat required to raise the temperature of an object by one degree Celsius.
• A good thermal conductor allows energy to pass quickly through it, while a poor thermal conductor slows down this process.
• Thermal equilibrium exists between two systems if they have equal average kinetic energies per particle.
• Energy can be transferred between objects by work done or heat flow.
• When an object moves at constant velocity, it does not have any acceleration.
• Thermal insulators have low thermal conductivity and prevent heat flow by trapping pockets of still air between fibers or layers.
• Thermal conductivity measures how easily a material transfers thermal energy by conduction.
• Heat flow is measured using a calorimeter, which measures the change in temperature of an object due to heating or cooling.
• Specific latent heat is the amount of energy required to change the state of one kilogram of substance without changing its temperature.
• Thermal insulators are materials that resist the flow of thermal energy by trapping pockets of still air between fibers or tiny bubbles.
• A good conductor has high thermal conductivity, while a poor conductor has low thermal conductivity.
• Latent heat is the energy transferred during phase changes such as melting or boiling.
• Latent heat is the energy transferred during phase changes such as melting or boiling.