ACTIVITY #1: Let’s Get the Ball Rolling!     Athletes, such as those depicted, frequently use the sloping ground to help them gain speed during an event. These athletes must be well aware of the changes in slope of the ground over the course of a run to be successful.   What is speed? How is it measured? What force is responsible for increasing the speed of the skier and the downhill street luge athlete? What could they do to increase their speed at the start of the race? What could they do to increase their speed during the race?  

Activity Overview: A synopsis of this lesson is as follows… GOALS: In this lab activity, you will … ·        Develop an appreciation for the need to collect several measurements of individual events to ensure a reliable result. ·        Calculate the speed of a ball that has rolled down a ramp. ·        Determine the relationship between the release height of a ball and the speed it reaches at the bottom of the ramp. (higher point-faster ball, repeat reliable results) Activity Overview: A synopsis of this lesson is as follows…   A ball is released from the top of a ramp. It rolls down the ramp onto a horizontal surface. When a hard ball rolls on a hard and level surface, its speed remains roughly constant. This speed is calculated using a distance predetermined by the teacher and the measured time needed for the ball to roll through this distance. The release height of the ball is then changed and the investigation repeated.

        The average speed of an object can be calculated by dividing the distance it travels by the amount of time needed to move through this distance. This relationship can be expressed by the equation Average speed = (distance traveled / time needed ) or Savg = D / T A free rolling object will speed up when rolling down an incline, but its speed will remain nearly constant on a level surface. When an object rolls down an incline, its speed at the bottom is determined by the height at which the ball was released.

Gather 5 wooden blocks, one golf ball, some tape, and one ruler. Let’s Investigate …   In this investigation section, you will find questions after certain steps in the procedure. These questions are meant to promote understanding of the key concepts in this activity. Write the answers to the questions in your science journal or science notebook. Gather 5 wooden blocks, one golf ball, some tape, and one ruler. Start with one wooden block resting on the table and then set the ruler at the edge of the block. Tape both ends of the ruler down so that it will not slide off of the wooden block.   3. Mark off a pre-determined distance on the table top (100 cm works well) starting near the bottom of the ruler. This distance will be the only portion of the ball’s motion that will be timed. (use 50cm and multiply by 2)

5.Repeat the task 4 more times at that height and 4. Release the ball from the top of the ramp and record only the time that it takes to cover your pre-determined distance 5.Repeat the task 4 more times at that height and then calculate the average time that it took the ball to cover the pre-determined distance. Record your results. 6.Use your calculated average time to now calculate the average speed of the ball.   Record the height of the ramp, the average time, and the average speed on your data table. 7. Increase the height of the ramp by adding another wooden block and then repeat steps #4,5, & 6 of the experiment.   Graph your results. Be sure to label your axes.

Investigation Reflection: Question #1: Why will the speed of the ball along the level tabletop be the same as the speed of the ball at the bottom of the ramp? (why speed-up down ramp and not on table?)   Question #2: Give a reason why the average time, calculated from 5 separate measurements, is more reliable than any single measurement of the time. Question #3: What effect did increasing the release height have on the speed of the ball? Question #4: Why do you think the speed of the ball depends upon its release height?  

In your journal or notebook, write a concise summary of this activity. Summary of Activity …   In your journal or notebook, write a concise summary of this activity. Be sure to address the following questions and use your data to support your responses. ü      How does height influence the speed of an object? ü      How does collecting multiple measurements during an investigation lead to a more reliable result?

Applying what you have learned …   Use what you have learned to explain why the water in streams flow swiftly in mountainous areas (like Colorado), but the water in streams in Delaware flows very slowly.