Unit B: Changes in Motion

Chapter 2: Collisions


Goaly:  Courtesy Getty Images
A goaltender in hockey needs to wear protective gear against speeding pucks. Some hockey players are able to shoot a puck at speeds of over 150 km/h! When designing such protective gear, like masks, the designer must have a good understanding of the forces associated with the motion of objects—especially colliding objects. 




Turn to page 240 of the textbook, and read the chapter introduction.
To slow down gradually, a driver may simply take his or her foot off the gas pedal before applying the brakes. As the vehicle “coasts,” it slows down. Many objects slow down after being set in motion. For example, a sliding hockey puck or a rolling marble eventually comes to a stop.

Significant characteristics of objects in motion can be learned by investigating marbles in motion.


  • Read the entire activity on page 241 of the textbook.

    Your teacher may be able to provide you with the U-shaped channel shown in the diagram on page 241. If you can obtain the U-shaped channel, do Path 1. If the channel is unavailable, do Path 2.

  • Follow the directions in the activity, and answer the questions.

    Check your answers with those in the “Suggested Answers” in the online course.
  • Use the sample data for this activity in the “Suggested Answers” in the online course to answer questions 1 to 5 on page 241.

    Check your answers with those in the “Suggested Answers ” in the online course.