Lesson 5
circumference of wheels
Unit 3
measuring circles
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5.1 Warm Up: A Rope and a Wheel
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Learning Targets
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your teacher will give you a circular object
5.2 Rolling, Rolling, Rolling
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5.2 Rolling, Rolling, Rolling
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5.2 Rolling, Rolling, Rolling
4. If you wanted to trace two complete rotations of your object, how long of a line would you need?
5. Share your results with your group and record their measurements in the table.
6. If each person in your group rolled their object along the entire length of the classroom, which object would complete the most rotations? Explain or show your reasoning.
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5.3 Rotations and Distance
1. A car wheel has a diameter of 20.8 inches.
a. About how far does the car wheel travel in 1 rotation? 5 rotations? 30 rotations?
b. Write an equation relating the distance the car travels in inches, c, to the number of wheel rotations, x.
c. About how many rotations does the car wheel make when the car travels 1 mile? Explain or show your reasoning.
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5.3 Rotations and Distance
2. A bike wheel has a radius of 13 inches.
a. About how far does the bike wheel travel in 1 rotation? 5 rotations? 30 rotations?
b. Write an equation relating the distance the bike travels in inches, b, to the number of wheel
rotations, x.
c. About how many rotations does the bike wheel make when the bike travels 1 mile? Explain or show your reasoning.
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5.3 are you ready for more?
Here are some photos of a spring toy. If you could stretch out the spring completely straight, how long would it be? Explain or show your reasoning.
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5.4 Rotations and Speed
The circumference of a car wheel is about 65 inches.
1. If the car wheel rotates once per second, how far does the car travel in one minute?
2. If the car wheel rotates once per second, about how many miles does the car travel in one hour?
3. If the car wheel rotates 5 times per second, about how many miles does the car travel in one hour?
4. If the car is traveling 65 miles per hour, about how many times per second does the wheel rotate?
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Lesson Summary
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5.5 Cool Down: Biking Distance
The wheels on Noah's bike have a circumference of about 5 feet.
1. How far does the bike travel as the wheel makes 15 complete rotations?
2. How many times do the wheels rotate if Noah rides 40 feet?
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Reflections
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Practice Problems
ALL PERIODS click here to submit homework.
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Lesson Video
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