Slide 1. Slide 2. Slide 3. General Problem-Solving. Find the Weight of the Block. General_Problem_Solving_slides.docx 9/7/07 MET 107

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1 Slide 1 General Problem-Solving MET 107 Slide 2 General problem-solving techniques Set aside some time to think about the problem before starting. Draw a sketch of the problem. Understand the overall purpose and the key points Determine what information is known INPUT DATA Determine what information is to be found OUTPUT DATA What fundamentals apply to the problem? Think about how you will solve the problem before actually solving the problem Develop your solution in an orderly and logical manner. Think about your answer. Does it make sense? Make sure your solution is clear and complete Slide 3 Find the Weight of the Block Unit Weight, γ =.28 lbs/in Weight = Unit Weight x Volume 1.5

2 Slide 4 Think About the Solution Methods Weigh a real part Solid model Find Volume & Multiply Times Unit Weight Face areas times thickness Break into known volumes and add together Slide 5 Purpose Find the weight of the block. Key Points Weight is unit weight times volume Rectangles and Circles Slide 6 Tools Scale Computer Spreadsheet Solid modeler Calculator

3 Slide 7 Input Data Unit weight, γ =.28 lbs/in 3 Dimensions of the block Output Data Weight of the block Known Fundamentals Volume of Right Rectangular Prism, V = W x H x D Volume of Cylinder, V cyl =.25 x π x d 2 x (D) Slide 8 Weigh It PART SCALE Slide 9 Analysis Tools in Solid Modeler From the Solid Model: V = in 3 W = 3.34 lbs

4 Slide 10 Area Times Thickness D 1 D 2 A 1 = 3 (1.5 ) (.75 ) -.25(π)(1.0 ) 2 A 2 = 1 (1.5 ) A 1 = 4.84 in 2 A 2 = 1.5 in 2 V = A 1 x D 1 + A 2 x D 2 = 4.84 in 2 (2.0 ) in 2 (1.5 ) V = in 3 W = γ V = 0.28 lbs/in 3 ( in 3 ) = 3.34 lbs Slide 11 Volumes 1 W = 4.0 H = 2.25 W = 2.5 H = 0.75 W = 1.0 H = 1.5 D = 0.5 = 1.0 V = 4.0 (2.25 )(2.0 ) (.75 )(2.0 ) - 1.0(1.5 )(0.5 ) -.25(π)(1.0 ) 2 (2 ) V = in 3 W = γ V = 0.28 lbs/in 3 ( in 3 ) = 3.34 lbs Slide 12 Volumes 2 W = 1.5 H = 2.25 W = 1.5 H = 1.5 W = 1.0 H = 1.5 D = 1.5 = 1.0 V = 1.5 (2.25 )(2.0 ) (1.5 )(2.0 ) + 1.0(1.5 )(1.5 ) -.25(π)(1.0 ) 2 (2 ) V = in 3 W = γ V = 0.28 lbs/in 3 ( in 3 ) = 3.34 lbs

5 Slide 13 Does the Answer Make Sense? Is the Solution Neatly Done? Is it Clear and Complete? Slide 14 Solving Problems w/ Computers INPUT PROBLEM SOLVING ALGORITHM OUTPUT Computer Slide 15 Computer Algorithms: Algorithm: the set of detailed, unambiguous, and ordered instructions developed to describe the transformations necessary to go from the initial (given) situation to the final (required) situation.

6 Slide 16 Required Algorithm Properties It must be sufficiently detailed to describe the transformations necessary to solve the problem. It must be unambiguous, so that anyone can perform the transformations correctly every time. It must always give the same results for the same initial conditions. It must give correct results in all cases. A process must meet these criteria to be considered an algorithm. In computer programming, the process used to solve the problem must be an algorithm. Slide 17 Algorithm An algorithm can be thought of as a series of one or more well-known operations. In order for an operation to be well known, it must meet the requirements of an algorithm. Slide 18 5 Things a Computer Can Do Perform arithmetic: add, subtract, multiply, and divide numbers. Compare two pieces of information and select one of two alternative actions, depending on the outcome of the comparison. Receive and put out information. Repeat any group of operations. Save any piece of information for later use. Any algorithm to be used on a computer must be stated in terms of the five well-known computer operations.

7 Slide 19 Flowcharts Flowcharts are useful for visualizing a set of transformations. A flowchart consists of certain symbols connected by arrows. Three commonly used symbols and their meanings are: Enter or exit the Start/Stop flowchart. (Start, stop, begin, end) Transformation Rule Perform a particular transformation. Ask a question; make a decision Question Slide 20 Flowchart Input or Output Receive or put out information Slide 21 Flow Arrows Arrows connecting flowchart symbols have two meanings: They show the order in which the transformations are to be performed They show the pathway or flow of given information going into a symbol and required information coming out.

8 Slide 22 Arrows Start One out End One In I/O Transformation Rule Question One in One out One in One out One in Two out