Name _________________________ Date: ________ Mathematical Fundamentals Purpose: To familiarize students with the mathematical principals and techniques to be utilized throughout the course. Goals: Upon successful completion of this lab assignment, students will be able to: 1. Read/write numbers in scientific notation. 2. Perform calculations using numbers expressed in scientific notation. 3. Use fundamentals of algebra to solve equations. 4. Use graphing techniques as a means of interpreting data. Scientific Notation An understanding of nature is built from measuring a wide variety of quantities. The quantities involved in astronomy pose a challenge to students because the values range from unfathomably large to infinitesimally small. For example, the distance to the star closest to our solar system, Proxima Centauri, is nearly 25,000,000,000,000 miles away. Such a large number can interfere with comprehension if it requires a reader to pause so he or she can figure out whether the number is referring to 25 million, 25 billion, or 25 trillion. To make reading move more smoothly, large numbers can be rewritten in different ways to make it easier to pick out the. One such technique is to write the distance to Proxima Centauri as, “25 trillion miles,” thereby eliminating unnecessary placeholders. A mathematical approach to shortening numbers is more useful for an introductory astronomy course. Unnecessary placeholders are eliminated mathematically by converting the placeholders to the proper power of ten. To see how this is accomplished, the distance to Proxima Centauri can be broken down as the multiplication of two numbers: 25,000,000,000,000 miles = 2.5 x 10, 000,000,000,000 miles We can then make use of the fact that the number 10,000,000,000,000 (10 trillion) can be rewritten as the number 10, raised to the 13th power (1013), and substituting it in the equality above: 25,000,000,000,000 miles = 2.5 x 1013 miles Values expressed in scientific notation are those that are written in the form as seen on the right hand side of the above equality. Essentially, scientific notation is the hand method for writing numbers that have many decimal places, mathematical short whether they are large or small. The main purpose for using scientific notation is to present numbers in a more readable form. Writing numbers in scientific notation involves separating the number into a mantissa and a power of ten. The mantissa is found by moving the decimal point of a given number so that there will be only one non- zero digit to the left of it, and then eliminating all unnecessary decimal place holders. Once the mantissa is determined, it will need to be multiplied by the appropriate power of ten. The appropriate power of ten amounts to the positive number of places the decimal point moved to the left or the negative number of places the decimal point moved to the right. Example 1 Rewrite the number 32,400 in scientific notation. Step 1: The mantissa is determined by moving the decimal point from the right of the zero to the right of the number three. The number we get is: 3.2400. Step 2: Eliminating unnecessary placeholders so that only three digits remain, we end up with a mantissa of: 3.24. Step 3: Multiply the mantissa by the appropriate power of ten by counting how many placeholders the decimal point was moved in order to obtain the mantissa. In this case, the power of ten is: 4. The number 34,200 is rewritten as 3.24 x 104. Example 2 Rewrite the number 0.0739 in scientific notation. Step 1: We obtain the mantissa by moving the decimal point to the right of the number seven, and then eliminating the zero. The mantissa we get is: 7.39. Step 2: The appropriate power of ten in this case is equal to the negative number of placeholders the decimal point was moved in order to obtain the mantissa. In this case, the power of ten is: -2. The number 0.00739 is rewritten as 7.39 x 10-2. Exercise 1: Write each of the following numbers in scientific notation. When writing each response, keep only three (3) digits in the mantissa and eliminate all other placeholders. Be sure to following proper rounding procedures. 1. 2,370 = 2.37 x 103 4. 12,094,000,000 = 1.21 x 1010 2. 0.00957 = 9.57 x 10-3 5. 0.000000004286 = 4.29 x 10-9 3. -459,090 = -4.59 x 105 6. -0.0005738 = -5.74 x 10-4 Calculations using numbers written in Scientific Notation In addition to making large numbers more manageable, scientific notation is useful in simplifying calculations, especially in cases where a scientific calculator is not available. By making use of the distributive property of mathematics, a person can compute a value by performing the calculation on the mantissa separately from the powers of ten. Then the resulting mantissa and power of ten can be combined when reporting the final answer. Below are some examples of this simplified method. Examples Multiplication (1.23 x 10 2 ) (2.46 x 10 3 ) = (1.23 x 2.46) (10 2 x 10 3 ) = 3.03 x 10 5 Division 8.48 10 9 (8.48 x 10 9 ) 5 = x 4 = 4.02 x 10 4 2.11 10 (2.11 x 10 ) Raising to a Power (2.92 x 10 3 )2 = (2.92) 2 x (10 3 )2 = 8.53 x 10 6 Taking a Square Root 1.44 x 1012 = 1.44 x 1012 = 1.20 x 10 6 Exercise 2: Perform the following calculations. Write each of your responses in scientific notation. When writing each response, keep only three (3) digits in the mantissa and eliminate all other placeholders. Be sure to following proper rounding procedures. 1. (4.32 x 10 4 ) (1.25 x 10 3 ) = 5.40 x 107 2. (3.38 x 10 7 ) = 7.35 x 104 2 (4.60 x 10 ) 3. (7.81 x 10 5 ) = 1.26 x 1012 (6.20 x 10 -7 ) 4. (4.35 x 1012 ) (6.62 x 10 -5 ) = 2.88 x 108 5. (7.71 x 1015 )2 = 5.94 x 1031 6. 2.25 x 10 8 = 1.50 x 104 7. (6.39 x 10 4 ) 3 = 2.61 x 1014 8. (5.08 x 10 ) Algebra Fundamentals 4 2 1.73 x 1010 = 1.16 x 105 8.65 x 1016 A major goal of scientific research is to find how various physical properties are related to one another. Once discovered these relationships are expressed as mathematical formulas, which are then verified through decades, and even centuries, of rigorous testing. Such relationships are referred to as laws of nature and we will be using them extensively throughout the course. The most basic use of a formula is to determine the value of one physical quantity based on the values of others through the process of mathematical substitution. For example, when a golf ball is hit off a tee, Newton’s 2nd law of motion (F = ma) can be used to determine how much force (F) was applied to get the golf ball moving using. In order to successfully use a formula to calculate a desired physical quantity, you must follow these steps: (1) Identify the correct formula to be used. (2) Substitute the given values for the proper variables. (3) Perform the calculation properly. Exercise 3: Choose the proper formula from the list provided and use the values given in each example to determine the value of the desired variable. Show your work by rewriting each function with the values substituted for the appropriate variable before recording your final result. In these examples, the variables have no physical significance. Formulas f = h - g(j) q = r - t u +v = - m = n 2 + op l2 9. Solve for q if r = 64, t = -16, u = - 11, and v = 19. 64- (-16) 64 + 16 80 , q = = = -11 + 19 19 - 11 8 q = 10 10. Solve for f if g = 2.14 x 103, h = 9.23 x 105, and j = 3.47 x 102. f = (9.23 x 10 5 ) - (2.14 x 10 3 ) (3.47 x 10 2 ) = (9.23 x 10 5 ) - (7.43 x 10 5 ) f = 1.80 x 105 11. Solve for m if l = 4, n = 5, o = 0.25, p = 44. m = (5) 2 + (0.25)(44) 25 + 11 36 = = , 2 (4) 16 16 m = 2.25 12. Solve for if = 7, = 32, = 1.5, = 30. = - 1.5 - (30 32) 1.5 - (960) (-958.5) = = = , 7 7 7 = -137 Even though scientific formulas are written in a standard form, it is possible to determine the value of any of the physical properties within the formula by changing around the equation. To successfully manipulate equations, basic rules of algebra must be followed to get a single unknown in an equation by itself. This is accomplished by applying inverse operations to both sides of an algebraic equation. Some useful inverse operations are listed below: Addition is the inverse operation of Subtraction (and vice versa) x +4 = 7 x + 4 (- 4) = 7 (- 4) x = 3 x - 8 = 11 x - 8 (+ 8) = 7 (+ 8) x = 19 Multiplication is the inverse operation of Division (and vice versa) x = 14 3 x (3) = 14 (3) 3 x = 42 5x = 125 5x 125 = 5 5 x = 25 Raising to a power is the inverse operation of taking a root (and vice versa) 3 x = 7 x 2 = 36 x2 = x = 6 x 3 36 3 = 7 3 x = 343 In many of the formulas that we will use in this course, there will be a combination of manipulations that will need to be applied. In these instances it will be important to to one side of an equation, the same remember the rule that whatever operation you apply exact operation must be applied to the other side. x2 + 15 = 63 3 x2 = 48 3 x 2 = 144 x = 12 Step 1 : Subtract 15 from both sides. Step 2 : Multiply both sides by 3. Step 3 : Take the square root of both sides. Exercise 4: Solve for y in each of the following examples by substituting all known variables and calculating a numerical value. Show your work by writing down all intermediate steps. 13. 19 = 3y + 5 19 - 5 = 14 = 3y 14 y = 3 14. y = 4.67 y - 7p = m, where m = -3 and p = 2. 4 y - (7)(2) = - 3 4 y = 44 y = 14 - 3 = 11 4 15. 3y 2 - 5x = 12, where x = 144. 3y 2 - 5(144) = 12 3y 2 - 720 = 12 3y 2 = 720 + 12 = 732 y = 15.6 2 y = 244 y = 16. 244 y - 5a = c , where a = 17, b = 9, and c = -4. b y - 5(17) = -4 9 y - 85 = - 36 y = 2401 y = 85 - 36 = 49 y = (49) 2 17. y = 12 + , where = 4.5, = 7.2, = 6.1, and = 3.14. (4.5) (7.2) = 12 (6.1) + 3.14 y 32.4 = 76.34 y = 0.424 y 32.4 = 76.34 y 32.4 = y 76.34 Essentials of Graphing Determining the laws of nature first requires that experiments be conducted to test the validity of any hypotheses that are proposed. During an experiment scientists will look for any changes in the value of a particular quantity (called the dependent variable) while another physical quantity (referred to as the independent variable) is adjusted. Once the measurements are made, scientists will then look for any relationships that may exist. The simplest method for determining any such relationships is by plotting the collected information on a graph. Basic graphing techniques involve being able to plot data points accurately on a graph and then determine any mathematical relationship that may exist. Below is a simple exercise that will illustrate how using a coordinate system can reveal information about a physical process. We will be using the standard Cartesian coordinate system that is taught in high school algebra. This system has the following characteristics: (1) A reference point called the origin (labeled as, O) (2) One horizontal axis (labeled, x) and one vertical axis (labeled, y) that run perpendicular to each other and cross at the origin. (3) Coordinates that are given in the form of (x ,y) such that the ‘x’ coordinate dictates how far along the horizontal axis a data point is from the origin, and the ‘y’ coordinate dictates how far along the vertical axis the data point is from the origin. 18. Table 1.1 contains coordinates for six (6) random points. Plot the points onto Graph 1.1 by placing a small, but legible, point at the proper coordinates. Be sure to label each point clearly. Table 1.1 Point x y A B C D E F -5 -1.5 6.5 -7.5 2 9 -4.5 3 0.5 6 8.5 -9.5 Graph 1.1 .E D . B . .C . A .F Graphing Measured Data 19. Table 1.2 lists the results of a hypothetical experiment where the distance traveled by a car on a road trip from NYC to Washington D.C. was noted every 45 minutes (or 0.75 hours). Plot the data points from the experiment onto Graph 1.2. Table 1.2 Time Since Beginning of Trip (t) Distance Traveled (d) 0.75 hours 1.50 hours 2.25 hours 3.00 hours 3.75 hours 4.50 hours 40.0 miles 110 miles 140 miles 176 miles 245 miles 280 miles 20. Hopefully it is apparent that there is an orderly relationship between the distance traveled and the amount of time traveled. The relationship gives the rate of change of distance with time and is referred to as the speed of the car. The speed of the car can be determined from the slope of the line that best fits the data points. (1) Using a straightedge (like a ruler), draw a single line that best fits the data points. This means drawing a line the best represents the relationship between the data points, rather than connecting the data points together. d (miles) Graph 1.2 . x . . . . x . t (hours) (2) Pick two arbitrary points that fall on the line you just drew and place a small (x) on each. These points should be far apart from each other and not include any of the data points from the table that you have already plotted. Write the coordinates of each point below: Arbitrary point 1: t1 = 0.5 hours d1 = 31 miles Arbitrary point 2: t2 = 4.7 hours d2 = 300 miles (3) The slope of the line will define the rate of change of distance with time. The slope (m) of any straight line is given as the ratio of the change in dependent variable (in this case, d) to the change in the independent variable (in this case, t). Use the formula below to calculate the slope of your line. Show the steps in your calculation. m = d d - d1 300 - 31 269 = 2 = = t t 2 - t1 4.7 - 0.5 4.2 m = 64 miles/hour (4) What property of the car does the slope of the line indicate? (Hint: use the units of measurement of the slopes as a guide) The slope of the line can be used to determine the average speed of the car during the trip.