Lesson 8

More about Constant Speed

Let’s investigate constant speed some more.

Problem 1

A kangaroo hops 2 kilometers in 3 minutes. At this rate:

  1. How long does it take the kangaroo to travel 5 kilometers?
  1. How far does the kangaroo travel in 2 minutes?

Problem 2

Mai runs around a 400-meter track at a constant speed of 250 meters per minute. How many minutes does it take Mai to complete 4 laps of the track? Explain or show your reasoning.

Problem 3

At 10:00 a.m., Han and Tyler both started running toward each other from opposite ends of a 10-mile path along a river. Han runs at a pace of 12 minutes per mile. Tyler runs at a pace of 15 minutes per mile.

  1. How far does Han run after a half hour? After an hour?
  2. Do Han and Tyler meet on the path within 1 hour? Explain or show your reasoning.

Problem 4

Two skateboarders start a race at the same time. Skateboarder A travels at a steady rate of 15 feet per second. Skateboarder B travels at a steady rate of 22 feet per second. After 4 minutes, how much farther will Skateboarder B have traveled? Explain your reasoning.

(From Unit 2, Lesson 16.)

Problem 5

There are 4 tablespoons in \(\frac14\) cup. There are 2 cups in 1 pint. How many tablespoons are there in 1 pint? If you get stuck, consider drawing a double number line or making a table.

(From Unit 3, Lesson 4.)

Problem 6

Two larger cubes are made out of unit cubes. Cube A is 2 by 2 by 2. Cube B is 4 by 4 by 4. The side length of Cube B is twice that of Cube A.

  1. Is the surface area of Cube B also twice that of Cube A? Explain or show your reasoning.
  2. Is the volume of Cube B also twice that of Cube A? Explain or show your reasoning.
Two larger cubes are made out of unit cubes. Cube A is 2 unit cubes wide, 2 unit cubes tall, and 2 unit cubes deep. Cube B is 4 unit cubes wide, 4 unit cubes tall, and 2 unit cubes deep.
(From Unit 1, Lesson 12.)