Physics Chapter on Motion

Motion

• Motion describes how an object's position changes over time.
• Speed is the rate at which an object moves. It's calculated by dividing distance traveled by the time taken.
• Velocity is a vector quantity that includes both speed and direction.
• Acceleration is the rate at which velocity changes over time. It can be positive (speeding up) or negative (slowing down or decelerating).
• Forces cause changes in motion, like starting, stopping, or changing the direction of an object.
• Newton's first law of motion (inertia): An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.
• Newton's second law of motion: The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. (F = ma)
• Newton's third law of motion: For every action, there is an equal and opposite reaction.
• Different forces can act on an object simultaneously. The net force is the sum of all the forces.
• Gravity is a force that pulls objects towards each other. The strength of gravity depends on the masses of the objects and the distance between them.
• Friction is a force that opposes motion between two surfaces in contact.

Energy

• Energy is the ability to do work.
• Potential energy is stored energy due to position or shape.
• Kinetic energy is energy of motion.
• Types of energy include: mechanical, thermal, chemical, electrical, electromagnetic, and nuclear energy.
• Energy can be transferred from one object to another or transformed from one type to another.
• The law of conservation of energy states that energy cannot be created or destroyed, only transferred or transformed.
• Examples of energy transformations include: a car engine converting chemical energy into mechanical energy and a light bulb converting electrical energy into light and heat energy.
• Work is done when a force causes an object to move in the direction of the force. Work = Force x Distance.

Matter

• Matter is anything that has mass and takes up space.
• Matter is made up of atoms, which are the smallest unit of an element.
• Elements are substances that cannot be broken down into simpler substances by chemical means.
• Compounds are formed when two or more elements chemically combine.
• Mixtures are combinations of two or more substances that are not chemically bonded.
• Physical properties of matter include color, texture, density, melting point, boiling point, and conductivity.
• Chemical properties describe how a substance reacts with other substances, such as flammability and reactivity.

Simple Machines

• Simple machines are mechanical devices that make work easier by changing the direction or magnitude of a force.
• Common simple machines include: levers, pulleys, inclined planes, wedges, screws, and wheels and axles.
• Each simple machine has a mechanical advantage which is the ratio of the output force to the input force.
• The efficiency of a simple machine is a measure of how much work is output compared to the work input.

Electricity and Magnetism

• Electricity is the flow of electrons.
• Static electricity is caused by the build-up of electric charges.
• Current electricity is the continuous flow of electric charges.
• Circuits are pathways for electric current to flow.
• Magnets have north and south poles. Like poles repel, and opposite poles attract.
• Magnetism is a force that attracts or repels certain materials.
• Electromagnetism is the interaction between electricity and magnetism.

Sound

• Sound is a form of energy that travels as waves.
• Sound needs a medium (like air, water, or solids) to travel.
• The speed of sound varies depending on the medium.
• Sound is produced by vibrations.
• Characteristics of sound include pitch, loudness, and quality.
• Sound waves have different frequencies, which determine the pitch.
• Loudness is related to the amplitude of the sound wave. Larger amplitude creates louder sounds.
• Quality describes the unique tone or timbre of a sound.

Light

• Light is a form of electromagnetic radiation.
• Light travels in straight lines called rays.
• Light can be reflected, refracted, and absorbed.
• Reflection is the bouncing of light off a surface.
• Refraction is the bending of light as it passes from one medium to another.
• Absorption is the process of a substance taking in light.
• The color of an object depends on the wavelengths of light it reflects.
• Light has properties of both waves and particles.
• Different wavelengths of light make up the visible spectrum (ROYGBIV).

Heat

• Heat is a form of energy transferred from a warmer object to a cooler object.
• Temperature measures the average kinetic energy of the particles in an object.
• Heat transfer occurs in three ways: conduction, convection, and radiation.
• Conduction is the transfer of heat through direct contact between objects.
• Convection is the transfer of heat through the movement of fluids (liquids or gases).
• Radiation is the transfer of heat through electromagnetic waves.
• Thermal energy is related to the temperature and the amount of matter.