Newton's First Law, also called the Law of Inertia, states that objects at rest stay at rest and objects in motion stay in motion at constant velocity unless acted upon by an unbalanced force. This means objects resist changes to their motion.

Kinetic energy is calculated using the formula KE = ½mv², where m is mass in kilograms and v is velocity in meters per second. The result is in joules. For example, a 2 kg object moving at 3 m/s has KE = ½(2)(3)² = 9 joules.

Speed is a scalar quantity representing how fast an object moves, measured as distance divided by time. Velocity is a vector quantity that includes both speed and direction. Speed tells you how fast; velocity tells you how fast and in which direction.

PhET physics simulations are interactive virtual experiments. Simply select a simulation, use the controls to adjust variables like mass, force, or position, and observe how the system responds. You can pause, reset, and collect data just like in a real lab.

Force is calculated using Newton's Second Law: F = ma, where F is force in newtons, m is mass in kilograms, and a is acceleration in meters per second squared. This formula shows that force equals mass times acceleration.

Electric current is the flow of electric charge through a conductor. It's measured in amperes (amps). Current flows from higher electric potential (voltage) to lower potential. Ohm's Law relates current, voltage, and resistance: I = V/R.

Newton's three laws are: 1) Law of Inertia - objects resist changes in motion, 2) F = ma - force equals mass times acceleration, 3) Action-Reaction - for every action there is an equal and opposite reaction.

Solve physics problems systematically: 1) Identify given information, 2) Determine what you need to find, 3) Draw a diagram, 4) Choose the appropriate physics principles, 5) Apply formulas, 6) Calculate the answer, 7) Check if the result is reasonable.