Mechanics Investigation: The journey of a marble AIM: To investigate the journey of a toy marble using our knowledge of mechanics. EQUIPMENT: Retort stand, 3 x meter ruler, 2 x stopwatch, marble, scales. METHOD: Find a clear section of carpet, set the ramp height, make sure there is a clear area for the marble to travel to a stop after leaving the ramp. Release the marble from the top of the ramp, and take the following measurements: T1 = time to reach the end of the ramp. T2 = how long the marble takes to reach a stop. D1 = distance from the end of the ramp to the marble. Repeat the experiment 3 times. NB: Assume constant acceleration to the end of the ramp and constant deceleration once off the ramp. USEFUL FORMULAE F = ma Ek = ½ mv2 Ep = mgh a = Δv / Δt v=d/t Use a set of digital scales to measure the mass of the marble: Convert this mass to kg: Calculate the weight of the marble: EXPERIMENT 1: Ramp height 15cm 1 2 3 Average. T1 T2 D1 1. Sketch a distance time graph. 2. Calculate the average speed (vav) ­for section 1 of the marbles journey where the marble accelerates down the ramp. 3. Calculate the maximum speed for section 1 (= 2 x vav) 4. Sketch a speed time graph for the journey: 5. Calculate the acceleration for section 1: EXPERIMENT 2: Ramp height 30cm 1 2 3 Average. T1 T2 D1 1. Sketch a distance time graph. 2. Calculate the average speed (vav) ­for section 1 of the marbles journey where the marble accelerates down the ramp. 3. Calculate the maximum speed for section 1 (= 2 x vav) 4. Sketch a speed time graph for the journey: 5. Calculate the acceleration for section 1: 6. Calculate the deceleration for section 2: 6. Calculate the deceleration for section 2: 7. Use the graph to calculate the total distance travelled: 7. Use the graph to calculate the total distance travelled: 8. Compare this calculated value to the actual distance travelled: 8. Compare this calculated value to the actual distance travelled: 9. Draw a force diagram for the marble in Section 2: 9. Draw a force diagram for the marble in Section 2: 10. Calculate the Net force in section 2 using your answer from 6: 10. Calculate the Net force in section 2 using your answer from 6: 11. Calculate the kinetic energy of the marble at the bottom of the slope: 11. Calculate the kinetic energy of the marble at the bottom of the slope: 12. Calculate the Potential energy of the marble at the top of the ramp: 12. Calculate the Potential energy of the marble at the top of the ramp: 13. Compare the calculated value for Ep to the Ek in part 11: 13. Compare the calculated value for Ep to the Ek in part 11: 14. Use the principle of energy conservation and the answer from 12, to calculate the expected speed at the bottom of the ramp, what assumption must be made? 14. Use the principle of energy conservation and the answer from 12, to calculate the expected speed at the bottom of the ramp, what assumption must be made? 15. Compare the calculated value for the speed in part 14 to the maximum speed calculated in part 3, provide an explanation for the difference: 15. Compare the calculated value for the speed in part 14 to the maximum speed calculated in part 3, provide an explanation for the difference:
