Lab-6

Heading Lab #17: Impulse Of A Baseball Group 6: Alyssa, Mike, Gabby, Jessica Period 4 Date Completed: February 4, 2010 Date Due: February 8, 2010


 * Purpose/Objective: The purpose of this experiment is to find the velocity of the softball being thrown.

Hypothesis: The velocity initial will be greater than the velocity final. The initial velocity it when the ball leaves the person's hand, and the final velocity is when the ball hits the box.

Excel Spread Sheet:

Calculations: 1. W = f X d X cos of the angle W = 5.5 X .085 (ignore cos180) W = .4675 J

2. KE = W KE = .4675 J

3. .4675 = 1/5 mv(squared) .4675 = 1/2(.782)v(squared) .344 = v

4. momentum = mv momentum = .782(.344) momentum = .269 kg(m/s squared)

5. impulse = momentum impulse = 1.82(5.556) impulse = 1.01 J

6. mv = (mass of ball + mass of box)(v squared) (.182)v = .85 v = .85/.182 m/s squared

7. Percent Difference = v initial - v initial calculated / average v initial X 100 Percent Difference = 5.56 - 4.68 / 3.22 X 100 Percent Difference = 27%

**Discussion Questions: 1. We made the assumptions that the angle measurement was 180 degrees, which effected each of the calculations. 2.We could have calculated the initial velocity by using kinematics. We could have measured the distance from where the ball was thrown, timed the ball in the air and made the final velocity zero. 3. The impulse-momentum relationship is useful because if you know one of them, you immediately know the other, since impulse and momentum are equal. This describes Newton's third law, which says describes the direct relationship between these two things. //A varying, one-dimensional force acts on a 50 kg mass as shown in the following graph.// 4. Magnitude of the impulse delivered to the object: J=F*T J=(1000N)(.05s) J=50 N/s 5. The change in the object's momentum is 50 because the Impulse is equal to the Momentum. 6. Final Velocity: m(Vf-Vi)=impulse 50(Vf+10)=50 Vf+10=1 Vf=-9 m/s 7. The magnitude of the "average force" acting on the object during the time graphed was 100 N/s (0.05)*(1000)+(0.10)*(1000)/2=100 N/s

Conclusion: This experiment proved our hypothesis correct. The initial velocity was greater than the final velocity. However, there were a few experimental errors. The box might have not started in the same spot as it did the times before, and how fast the softball was thrown could change the answers, specifically affecting time and velocity. To fix this problem, placing the box next to a straight object or marking the floor with the box's dimensions would make sure the distance is more accurate. To have more accurate timing and speed, using a pitching machine would be helpful because you can set the time and speed for each pitch, which would make the results much more accurate. Due to lack of equipment, some of the calculations could have been off.