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Chapter 4, Lesson 8 Rate-Time-Distance Problems. By:A. s. Objective: To solve word problems involving uniform motion. An object is in uniform motion when it moves without changing its speed, or rate.
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An object is in uniform motion when it moves without changing its speed, or rate.
Example:Two jets leave Denver at 9:00 A.M., one flying at a speed 50 km/h greater than the other which is traveling west. At 11:00 A.M., the planes are 2500 km apart. Find their speeds.
Step 1: Explore: The problem asks for the jets’ speeds.
Step 2: Assign Variables X=Jet 1’s Speed, and X+50=Jet2’s speed because it is flying 50km/h faster than jet 1.
Step 3: Plan: Write an equation 2x+2=2(x+50)=2500
Step 4 Solve: 2x+2(x+50)=2500 2x+2x+100=2500 4x+100=2500 4x=2500-100 4x=2400 X=600=Jet 1 X+50=650=Jet 2
Step 5: Check and write your answer in a sentence. Jet 1 is flying at a rate of 600 km/h, and Jet 2 is flying at 650 km/h.