2. Chapter 4, Lesson 8 Rate-Time- Distance Problems By:A. s.

3. Objective: To solve word problems involving uniform motion.

4. An object is in uniform motion when it moves without changing its speed, or rate.

5. 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.

6. Step 1: Explore: The problem asks for the jets’ speeds.

7. 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.

8. Step 3: Plan: Write an equation 2x+2=2(x+50)=2500 Rate xTime =Distance Jet 1x22x Jet 2x+5022(x+50)

9. 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

10. 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.