Physics Review: Forces and Motion

Forces and Motion

• Position is the location of an object
• Motion is movement that changes an object's position
• Speed is the distance moved in an amount of time
• Velocity is the speed and direction of a moving object
• Inertia is the tendency of an object in motion to stay in motion or an object at rest to stay at rest
• A force is a push or pull
• Acceleration is a change in speed of an object
• Friction is the force that works against motion
• Gravity is the force that pulls objects down toward Earth

Changing Motion

• Newton is the unit used to measure force
• Balanced forces are forces that are equal in size with opposite directions
• Unbalanced forces are forces that are not equal in size with opposite directions
• When mass increases, acceleration decreases
• When force increases, acceleration increases

Work and Energy

• Work is done when force is used to move an object a distance
• Energy is the ability to do work
• Potential energy is stored energy
• Kinetic energy is the energy of motion (movement)
• Energy can be transferred from one object to another
• Energy can be transformed from one form to another
• Types of energy: chemical, light, thermal, electrical, mechanical, and nuclear

Heat

• Heat is the flow of thermal energy from one object to another
• Temperature measures the thermal energy of the particles in a substance
• Thermometers measure temperature using liquid mercury inside
• Conduction is heat transfer between two objects that are touching
• Convection is heat transfer through liquids or gases
• Radiation is heat transfer through space (no matter is needed)
• Insulators are materials that do not transfer heat energy easily (cotton, plastic)
• Conductors are materials that transfer heat energy easily (metal)

Sound

• Sound travels in solids, liquids, and gases
• Sound cannot travel through outer space since there is no matter in space
• Wavelength is the distance between waves
• Frequency affects pitch
• Amplitude affects volume
• Pitch is the highness or lowness of sound
• Volume is the loudness of a sound

Light

• Light travels in waves
• Transparent materials (glass) allow light to pass through
• Translucent materials scatter light in different directions
• Opaque materials block light completely
• Colors of visible light: ROYGBIV (Red, Orange, Yellow, Green, Blue, Indigo, Violet)
• Red has the longest wavelength, Violet has the shortest wavelength
• Reflection is when light waves bounce off a surface
• Refraction is when light rays bend when moving from one material to another

Electricity

• Electrical charges can be negative or positive
• When a lot of charges build up, it's known as static electricity
• A circuit is a path where electric current flows
• The flow of electrical charges through a circuit is called electric current
• Electrical conductors are the same as heat conductors (metal)
• • and - charges attract each other
• • and - charges repel each other
• • and + charges repel each other
• Fuses can only be used one time and break the connection when there is too much electricity/heat