Warm-up • Determine the SPEED of a rocket that traveled 148 meters in 7.0 seconds. (Show ALL steps) • Round to nearest tenth. Make sure to add a label.
Answer • 148 / 7 = 21.1 m/s • Raise both hands if you have it correct.
Marble Speed Lab By Mr. Harvey As a result of this lesson you will be able to calculate the speed of a moving object and determine factors that affect motion.
ProceduresStep 1 • Find a space on the floor that is smooth and level for a distance of about 1.5 meters. • You must be able to see the second hand on a watch, stop watch, or clock. • Sit down with your group once you find your spot and place one hand on your head when you are ready to move forward. (You will do this when your group finishes each step of the lab.) 3
Materials Needed(2 minutes to gather) • two grooved metric rulers per group • 2 meter sticks per group • one marble per group • 1 answer sheet per person in group • 1 Calculator per group • 1 Stop watch per group • 1 pencil per person in group • 2 science books • Please do not bounce or play with the marble! • http://www.youtube.com/watch?v=fjWM_KnjvPY 0
Materials that you should have in your area: • http://www.youtube.com/watch?v=hvEg2gH2gg8
Step 2 • Place a ruler so that one end is raised 1.5 cm at the 25cm mark, and the other end is on the floor. • Hint: Use your science book and turn to a page that creates the correct height. Close your book and re-check the height. 2
Step 3 • Using a marble, how can you tell if the floor is level? • Discuss the answer with your group and write down what you think on your answer sheet in the space provided. • Please use complete sentences. 3
Step 4 • Roll a marble down the groove and onto the floor. Start the marble from the higher end of the ruler at the 25 cm mark. • Measure and record how far the marble rolls in two seconds. Start measuring from the bottom end of the ruler where it touches the floor. Don’t start to count until the marble hits the floor. 2
Step 5 • Repeat step 4 procedure three times. Record the distance each time on your answer sheet in chart 1.5.2.
Step 6 • To find the average distance the marble rolled in two seconds, add together the three distances measured for a total number. Divide this total number by three. • Write the average distance in the box labeled average distance on chart 1.5.2 • Make sure to label the correct units. 3
Step 7 • S=D/T To find the average speed of the marble, divide the average distance traveled by the time it takes to travel that distance. For instance, if the marble rolled 30 centimeters in two seconds, its average speed would be 30 cm ÷ 2 seconds or 15 cm per second (15 cm/s). Write the average speed per second after letter B on your answer sheet. Remember to label.
Step 8 • Determine how far the marble rolls from the end of the ruler in 3 seconds. • Measure and record three more trials. • Record your measurements in chart 1.5.3 3
Average speed for 3 seconds. • Complete number 3 on sheet.
Step 9 • Place another ruler at the lower end of the first ruler so that the marble will pass directly from one ruler onto the other. Make sure that the zero ends of the rulers meet in the middle. • Raise the far ends of both rulers 1.5 cm above the floor.
Step 11 • Prediction: If the marble is released from the 25 cm mark on one ruler, predict how high the marble will role up the second ruler. • Write your prediction in a complete sentence on number 4 of your answer sheet. • Example: http://www.youtube.com/watch?v=rbuncwAiiHE • Test your prediction. Write your result on number 5 of your answers sheet. 3
Step 11 • Answer the rest of the questions on your answer sheet. • When you have finished, turn-in your answer sheet and put all materials back where they belong.
6. Is the average speed of the 3 second runs >, <, or = to the average speed during the 2 second runs?Explain why. • The average speed of the 3 second run is less than the two second run because the marble had more time to slow down due to friction.
7. If the direction in which the marble was rolling was included, what would the measurement be called? • Velocity
8. What two forces are affecting the motion of the marble? • Friction and gravity
9. Why can we say that the marble is accelerating throughout its motion? Because it is speed up, slowing down, and changing direction.
10. List 5 factors that you think affected the speed of your marble. • Dust on floor • Floor surface • Cracks in floor • Friction • Type of marble • If floor was level • Smoothness of ruler
The End Congratulation!!!!