Lab-2

Group 2: Chet Palumbo, Scott Weinstein, Sarah Spellman, Kelly Murphy

Impulse of A Softball Period 4 Completed: 2-2-10 Due:2-8-10 Kelly Murphy, Sarah Spellman, Scott Weinstein, Chet Palumbo


 * Objective**- The purpose of this lab was to calculate the velocity of the softball while it is thrown into a box.


 * Hypothesis**- The greater the velocity of the ball, the more force it will have when hitting the box, causing the box to slide further. Because force is directly related to acceleration, the faster the acceleration and velocity, the more force the ball will have to move to the box.

mass of softball (kg): .183 mass of packed boxed (kg): 1.44 total mass of packed box and softball (kg): 1.623 Data Studio Graph:
 * Excel Data Table**

1. W= F*D*Cos(angle) W= 6.7*.147* Cos(90) W= .911J
 * Sample Calculations**:

2. KE= 1/2mv^2 KE= 1/2 (1.623) (1.123105)^2 KE= .911 J

3. KE= 1/2mv^2 V=KE/(.5)m V= .9114/.9115 V= 1.123 m/s

4. Momentum= (Mball+Mbox)V2 = (.183+1.44)1.23 Momentum= 1.8228 kgm/s

5. Impulse= Mball/box*(Vball/box) Impulse= 1.623(1.123) Impulse= 1.8228 N sec

6. Velocity= __Mball/box*(Vball/box)__ Mball Velocity = __1.623(1.123)__ .183 Velocity= 9.96m/s

7.%= __|Actual- Theoretical|__ x100 Theoretical %= |__9.98- 11.12|__ x 100 11.12 % Difference= 10.82%

8. Average:Vi of ball from DS + Calculate Vi of ball/2 11.12+9.979/2= 10.549


 * Discussion Questions**:

1. What Assumptions did you make in order to complete the calculations in this experiment? - We assumed that the initial velocity was the fastest velocity.

2. How else could you have calculated the initial velocity? - You could have calculated using kinematics as well as dynamics. You were given the mass, the friction force, the distance traveled, and the final velocity. Therefore you could use all of these to find acceleration, and then use that in a kinematics equations to derive your answer.

3. Why is the impulse-momentum relationship a useful one? - This relationship is useful because it perfectly demonstrates Newton's third law, when there is an impulse of something the momentum of the object is directly related because they are the exact same force, according to Newton's third law.

4. Find the magnitude of the impulse delivered to the object J=F*t J=(1000 N)(.05s) J=50 N.S.

5. Determine the change in the object's momentum. Because of the impulse-momentum change relationship, the object's change in momentum is 50 because that is what it's impulse is equal to. Momentum equals impulse.

6. If the object's original velocity was -10m/s, calculate its final velocity. m(Vf - Vi) = impulse. 50 (Vf +10) = 50 Vf +10 = 1 Vf = -9 m/s

7. What was the magnitude of the "average force" acting on the object during the time graphed? (0.05)(1000) + (0.10)(1000) / 2 = 100 N.s

The purpose of this lab was satisfied because we were able to calculate the velocity of the softball as it was thrown into the box. Our hypothesis was proven correct because the force of the ball on the box was able to move the box a certain distance because of the velocity it had when it collided with the box. The greater the velocity of the ball, the more force it will have when hitting the box, creating the box to move further backwards. An example of this is when the velocity of the ball was 9.98 m/s when it made contact with the box, causing the box to move .147 meters**. In this lab, there was little room for error, therefore there was not a huge percent difference. The percent difference ranged from 11.068% to 3.536%. The error could have occurred in the distance the box traveled. When the ball was thrown into the box to make the box move backward, the box could have spun to the side a little, cause a loss of energy. This could have resulted in not getting the full distance it was capable of having. Also, the ball had masking tape attached to it, connecting the tape used to collect information on data studio. This tiny bit of extra mass could have affected the velocity of the ball. However, with our results of a very low percent difference, these errors obviously didn't make a huge impact. ** In order to address all of these errors, there is one solution. That would be to use a pitching machine. With this machine, the ball would have the same initial velocity almost every time, the same speed approaching the box, and it would be thrown from the same place every time. This would give the best results because we could line it up so that it would hit the box right in the middle, therefore causing the box to move straight back, instead of turning to the side upon impact. The pitching machine would provide the best results. This lab has several real life applications, however one that it is very similar to this lab is the firing of a bullet. Once a bullet is fired, it hits the object and the object is set back in motion, just like the ball did to the box in this lab.
 * Conclusion : **