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Introduction to Physics. What is physics?. Physics is a branch of science that involves the study of the physical world: energy, matter, and how they are related. In physics, we use mathematics in many ways to explain how matter and energy are related. Problem Solving.
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What is physics? • Physics is a branch of science that involves the study of the physical world: energy, matter, and how they are related. • In physics, we use mathematics in many ways to explain how matter and energy are related.
Problem Solving • The process of solving the problem is more important than the answer. • Therefore showing work in necessary in all cases.
Read and analyze the problem. • Identify all the known and the unknowns. • Use the units as hints. • The potential difference, or voltage, across a circuit equals the current multiplied by the resistance in the circuit. That is, V (volts) = I (amperes) × R (ohms). What is the resistance of a lightbulb that has a 0.75 amperes current when plugged into a 120-volt outlet?
Knowns and Unknowns • 0.75 amperes= I • 120 Volts= V • What are you trying to find? = Resistance
Write the base equation. • V = I x R
Substitute the values in the equation. • V = I x R • 120 = 0.75 x R
Evaluate the answer. • Are the units correct? • Is the answer reasonable?