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Investigation 3 – PostLab









Refer to the two graphs you created to illustrate the effect of weight on frictional force and the effect of surface area on the frictional force.

Focus on the relationships illustrated with these two graphs.

  • What is the relationship between weight and frictional force?
  • What is the relationship between surface area and frictional force?

Note: You have an additional prompt in your Data Record that suggests you might benefit from using the “What’s New?” Thinking Tool. Reflect on your previous understanding regarding friction, particularly if you had any misconceptions or if you are surprised by your results.

Apply your conclusions about friction to real-life situations. Read each of the following scenarios and apply your experimental results.

  • Your teacher will draw the following diagram on the board:

FRICT3_box pic

  • Imagine that you must move a box full of books to the next room. The dimensions of the box are 100 cm by 20 cm by 20 cm. The box is too difficult to carry and must be pushed along the floor. How could you make pushing the box easier? 
  • Your older brother has just gotten his driver’s license, and he is eager to drive his small two-door car. However, it is mid-winter, and the roads are often covered with snow and ice. Your parents want your brother to be safe when he drives. What can your parents do to keep your brother’s car from sliding on the slick roads? 


Complete the Focus Questions in your SDR then discuss them as a class. 

  • What is the relationship between weight and frictional force? 

  • What is the relationship between the surface area of an object in contact with another surface and the frictional force between two surfaces?