Objective To calculate the speed of a sliding puck while testing a variety of surfaces in association with frictional forces

Materials Hockey pucks, 1’ X 4’ wooden ramps (about 115 cm long), waxed paper, aluminum foil, meter sticks, stopwatches

Estimated Time 30 minutes (This is provided as a guide, as all activities can be lengthened or shortened as necessary).

CA State Science Standards 6th grade I&E7b, c, e; 7th grade I&E7a, c, e; 8th gradePS1b, c

Video Support Content

NA

The Science

Friction is a force that acts to oppose motion. The amount of friction between two surfaces is classified as the coefficient of friction.

Student Activity

Prop up a wooden board against a wall to use so the puck will slide down the surface without being pushed. Below are the recommended specifications:

Once the board is set up as suggested above, slide a puck 10 cm. from the top edge of the board and let the puck slide. Time the sliding puck from start to finish and record the number of seconds needed. Then cover the surface of the board with the materials listed (one material at a time) and repeat this activity.

Surface Trial 1 (sec)

Trial 2 (sec)

Trial 3 (sec)

Average Time (sec)

Average Speed (cm/sec)

Wood

Waxed Paper

Aluminum Foil

Perform multiple trials, then average the amounts of seconds required for the puck to slide down the board. Calculate the speed of the puck by dividing the distance traveled by the average number of seconds needed. Discuss the results of this experiment. Which surface did you initially think would be the fastest surface? Which surface actually proved to be the fastest surface? [Students may have different ideas about which surface will exhibit the least amount of friction, however, the wax paper will prove to be the fastest surface.] Extension Use reference books or the Internet to research how the coefficient of friction compares to when a puck slides across ice in relationship to when a puck slides across foil, wood or waxed paper. [Note: this can be an independent research project for the students.]

60 cm

115 cm

10 cm