MCAS Grade 8 Science cheat sheet
MCAS Grade 8 Science · Keep the key ideas within reach.
Grade 8 Science (Massachusetts STE Standards)
Motion: speed = distance ÷ time; velocity adds direction; acceleration = change in velocity ÷ time and occurs whenever speed, direction, or both change.
Newton's laws: an object at rest or in uniform motion stays that way unless a net force acts; net force = mass × acceleration (F = ma); forces come in equal, opposite pairs acting on different objects.
Gravity and mass: weight is the gravitational force on an object and changes with location, while mass (amount of matter) stays the same; gravitational attraction increases with mass and decreases with distance.
Kinetic energy = ½mv², so doubling speed quadruples kinetic energy; potential energy increases with height and mass (gravitational PE = mgh near Earth's surface).
Energy is conserved in a closed system but transforms among forms (motion, gravitational, elastic, thermal, chemical, electrical, light); friction converts mechanical energy to thermal energy.
Waves transfer energy, not matter; wave speed = frequency × wavelength; frequency and wavelength are inversely related when speed is constant.
In a series circuit there is one path and current is the same everywhere; in a parallel circuit there are multiple paths, and adding a parallel branch lowers total resistance and increases total current.
Electric and magnetic effects are related: a changing magnetic field can induce a current, and current-carrying wires produce magnetic fields (basis of motors and generators).