UMass Amherst KIN 430 - Biomechanics Lab C (2 pages)

Emily Weimer Biomechanics Laboratory C Projectile Motion Part 1 Sensitivity of performance to speed angle and height Release conditions Flight 1 Flight 2 Average Sh Sh Sh speed angl e height Nominal case 12 cm 20 Floor 167 64 148 157 82 25 speed 15 cm 20 Floor 223 238 230 5 50 angle 12 cm 30 Floor 193 189 191 170 height 12 cm 20 Floor box 161 200 180 5 Which manipulation provides the best benefit based on increase Compute the percent change in horizontal displacement Sh of the projectile you would expect if you increased speed angle or height by 20 manipulations compared with the nominal case 20 speed 36 84 provides best benefit based on increase 20 angle 8 41 20 height 1 69 Questions to be answered 1 a Horizontal displacement was most sensitive to which of the three release factors Explain why the horizontal displacement was most sensitive to this release factor Hint consider how vv vh and ttot are affected by changing the release factors noting that sh vh ttot and increases in either vv or height will increase t tot Out of the three different release factors horizontal displacement was most sensitive to the speed of release Increasing the release speed results in increased an increased horizontal and vertical velocity which results in an increased horizontal displacement Increasing the speed also increases the amount of time the rubber band will spend in the air Part 2 Different solutions to the same problem Speed Angle Case 1 14 cm 25 Case 2 15 cm 10 Question to be answered 3 Based on your results describe how speed affects technique reflected by release angle and horizontal displacement max sh Through this trial and error process of finding the right speed and angle to hit the target we were able to see how speed affected both horizontal displacement and release angle In order to hit the target we had to increase the speed which also required us to increase the angle of the launch We were then able to increase the speed 1 cm which required us to decrease the angle by 15 degrees Although horizontal displacement is affected greater by increasing speed if we had increased the speed by 1 and hadn t decreased the angle then the rubber band would ve flown over the target showing that the technique release angle also influences the horizontal displacement Part 3 The real thing A collision between theory and reality Trail Goal Angle Actual Angle Speed Height Vv Vh Ttot Sh 1 10 deg 11 4 deg 8 27 m s 1 62 m 1 63 m s 8 11 m s 765 s 6 2 m 2 20 deg 20 4 deg 7 38 m s 1 87 m 2 57 m s 6 92 m s 933 s 6 45 m 3 30 deg 29 6 deg 6 44 m s 2 08 m 3 18 m s 5 6 m s 1 05 s 5 89 m 4 35 deg 35 9 deg 5 93 m s 2 22 m 3 48 m s 4 8 m s 1 11 s 5 36 m 5 45 deg 44 1 deg 5 35 m s 2 35m 3 72 m s 3 84 m s 1 17 s 4 49 m Question to be answered 4 What happened to the speed and height of release as the angle of release was increased Were these changes what you would expect to observe Explain The speed decreased as the angle of release and height was increased The horizontal velocity is less when the height of release is increased because the speed also decreases Having an increase in height increases the vertical velocity which will result in a decreased horizontal displacement and horizontal velocity After conducting a few trials of adjusting the rubber band height and speed I was able to understand why this was happening 5 Which of the five cases resulted in the greatest horizontal displacement Does this make sense Explain The horizontal displacement was greatest in the second case When using the formula sh vh ttot the greatest displacement is seen in the second case The speed and release angle used in the second case result in the projectile being able to travel the further distance