Introduction Physics The study of energy There are five main branches in physics. Each branch represents a different form of energy. Mechanics The study of forces Acoustics The study of sound Thermodynamics The study of heat Optics The study of light Electricity and Magnetism Click to continue Physics is the study of energy Click to next slide Mechanical energy Sound is a form of energy Heat is a form of energy Light is a form of energy Electricity and magnetism are different forms of energy In simple terms, physics can be defined as “the study of energy”. Mechanics is the study of forces Acoustics is the study of sound Thermodynamics is the study of heat Optics is the study of light THE BRANCHES OF PHYSICS

Introduction Click to continue Intro to Mechanics is the port of entry into physics. A job well done in mechanics will form a solid foundation for the rest of the subject. NOTE Symbols and units Symbols are letters used in formulas. Units are letters used in quantities. Do not confuse symbols with units. CAUTION m represents mass t represents time F represents force v represents velocity W represents work etc. etc. Here are some examples kg kilograms for mass s seconds for time N newtons for force m/s meters/second for velocity J joules for work m meters for length etc. etc. Here are some examples Look! Some units use capital letters 20 kg 22.5 s 400 N -200 J Note that you will need to memorize the units because they are standard and cannot be changed and they are mandated by law. Mass Time Force Energy It is the unit that identifies what the quantiy represents. s d Note that we can change symbols at any time and use whatever symbols we like. For example

Introduction Click to continue Click to next slide All quantities have up to 4 parts: SignMagnitudePrefixUnit Quantities Note that the prefix is optional (it may or may not be included) Memorize the following prefixes (because they are used often) : m stands for “milli” and simply means “divide by 1000” u stands for “micro” and simply means “divide by ” k stands for “kilo” and simply means “multiply by 1 000” When entering quantities into a formula, be sure to remove the prefix (by multiplying or dividing) to reduce the quantity into the stanfard units. + or - a number Remember that the standard unit for mass is the kilogram.

Introduction Click to continue Click to next slide BASIC QUANTITIES There are three basic quantities in mechanics. Length Mass Time UNIT meter kilogram second All other quantities in mechanics are derived from these basic three and are known as “derived” quantities. NOTE Remember: Only these units are allowed in physics formulas! It is your responsibility to convert all quantities into basic units!

Formulas

Hypotenuse is double opposite side

While the value for g is 9.8 m/s 2, for quick practice, you may use 10 m/s 2 to simplify your calculations. From a past physics exam N O T E

Introduction Click to continue Slide 4 /xx Click to next slide DERIVED QUANTITIES Velocity Acceleration Force UNIT m/s The derived quantities in mechanics are derived from the basic three quantities (length, mass and time). Work Power meters/second etc. meters/second/second Velocity Derived from Acceleration Force OR meters/second 2 m/s 2 mass meters/second/second.. mass meters/second 2 OR Length/Time OR Length/Time/Time OR Mass Length/Time/Time. OR m/s 2

V (m/s) t(s) Example-1 Velocity-Time Graph Slope = acceleration Area = distance Note that the first 5 seconds is from t = 0 to t = 5 s. Thus, we need to find the distance under the curve from t = 0 to t = 5 s. Since the distance for the first 5 seconds consists of two segments, we will find the area in two steps. Step-1 is from t = 0 to t = 3 s (segment A) and step-2 is from t = 3 s to t = 5 s (segment B). A B Step-1: Area of sector A = (3 m/s x 3 s)/2 = 4.5 m Step-2: Area of sector A = (3 m/s x 2 s) = 6 m Step 1Step 2 Distance traveled = A + B = 4.5 m + 8 m = 10.5 m The graph on the left illustrates the velocity-time curve of a vehicle. Find the distance traveled by the vehicle for the first 5 s. TASK Answer Click to continue Click to next slide

V (m/s) t(s) Example-2 Velocity-Time Graph Slope = acceleration Area = distance Note that the area under the curve for this problem is from t = 4 s to t = 7 s and consists of only one section. Thus, all we need to do is find the area of the rectangle. Area under the curve = 3 m/s x 3 s = 9 m Distance traveled = 9 m Answer The graph on the left illustrates the velocity-time curve of a vehicle. Find the distance traveled by the vehicle between t = 4 s and t = 7 s. TASK Click to next slide Click to continue

V (m/s) t(s) Example-3 Velocity-Time Graph Slope = acceleration Area = distance Note that the area under the curve for this problem is from t = 9 s to t = 14 s. The area under the curve for this problem consists of two sections, a small triangle and a long rectangle. Area of triangle = (1 m/s x 1 s)/2 = 0.5 m Distance traveled = 0.5 m + 5 m = 5.5 m The graph on the left illustrates the velocity-time curve of a vehicle. Find the distance traveled by the vehicle during the last 5 seconds. TASK 1 m/s by 1 s Area of rectangle = (1 m/s x 5 s) = 5 m 1 m/s by 5 s Answer This is during the last 5 seconds. Click to continue Click to next slide

V (m/s) t(s) s d

Area of sector D = 6 x 1 = 6 m V (m/s) T s) Distance traveled = A + B + C + D = 4.5 m + 15 m + 2 m + 6 m = 27.5 m Area of sector C = (2 x 2)/2 = 2 m Example-1 Find the total distance traveled Answer

When objects hang motionless by way of a cord or wire they are in equilibrium and the force in the wire is called tension. When objects are suspended at an angle by a wire, the tension in the wire becomes greater as the angle increases. Consider a picture (and frame) hanging on a wall. The wire holding the picture consists of two sections; a left wire and a right wire. Both sections are identical. The tension in each wire (or section) is the same. This is because the lengths of the two wires are equal.

… and good luck!