1. Energy and Momentum in Hitting a Softball
Shaina Mann

2. Objects Used Softball: can vary in size and weight
Used a 6 oz (170 g) softball
Bat: can vary in size and weight
Used a 23 oz (652 g), .84 m bat

3. Question
Are energy and momentum conserved when hitting a softball off a tee?

4. Energy Kinetic: energy of motion Potential: energy of position
Linear: due to translational motion
Angular: due to rotation of object
Potential: energy of position
Total energy: Kinetic energy + Potential energy
In an isolated system, energy is conserved. This, however, is not an isolated system.
In hitting a softball, potential energy of bat  kinetic energy of bat  kinetic energy of ball

5. Momentum Linear: measure of an object’s translational motion
Angular: rotational analog of linear momentum
Total momentum: Linear + Angular
In an isolated system, momentum will be conserved. However, this is not an isolated system.
In hitting a softball, momentum of bat  momentum of ball

6. Forces at play Potential energies of bat and ball
Kinetic energies of bat and ball (angular and linear)
Momentum of bat and ball (angular and linear)
Energy and momentum of hitter
Elasticity of bat and ball
Heat generated by friction

7. Equations Needed Linear Kinetic Energy=1/2*m*v^2 (Joules)
Potential Energy=m*g*h (Joules)
Angular Kinetic Energy=1/2*I*w^2 (Joules)
Linear Momentum=m*v (kg*m/s)
Angular Momentum=I*w (kg*m^2/s)
Moment of inertia of rod (I)=m*L^2/3 or m*L^2/12 (kg*m^2)

10. Time vs. Linear Kinetic Energy
Bat
Moment of contact
Kinetic Energy (J)
Ball
Time (sec)
Kinetic Energy at moment of contact: 151 J
Difference: 59.2 J
Kinetic Energy at end of swing: 91.8 J

11. Time vs. Potential Energy
Bat
Potential Energy (J)
Moment of contact
Ball
Time (sec)
Potential Energy at moment of contact: 8.7 J
Difference: 9.7 J
Potential Energy at end of swing: 18.4 J

12. Time vs. Angular Kinetic Energy of Bat
Moment of contact
Angular Kinetic Energy of Bat (J)
Time (sec)

13. Time vs. Angular Kinetic Energy of Hitter
Moment of contact
Angular Kinetic Energy of Hitter (J)
Time (sec)

14. Time vs. Total Energy of Bat and Ball
Moment of contact
Total Energy of Bat and Ball (J)
Time (sec)
Total Energy at moment of contact: 305 J
Difference: 165 J
Total Energy at end of swing: 140 J

15. Time vs. Linear Momentum
Bat
Moment of contact
Momentum (kg*m/s)
Ball
Time (sec)

16. Time vs. Total Linear Momentum of Bat and Ball
Moment of contact
Total Momentum (kg*m/s)
Time (sec)
Total momentum at moment of contact: 14.8 kg*m/s
Difference: 3.6 kg*m/s
Total momentum at end of swing: 11.2 kg*m/s

17. Time vs. Angular Momentum of Bat
Moment of contact
Angular Momentum of Bat (kg*m^2/s)
Time (sec)

18. Time vs. Angular Momentum of Hitter
Moment of contact
Angular Momentum (kg*m/s)
Time (sec)

19. Time vs. Total Momentum of Bat and Ball
Moment of contact
Total Momentum of Bat and Ball (kg*m/s)
Time (sec)
Total Momentum at moment of contact: 24.7 kg*m/s
Difference: 10.2 kg*m/s
Total Momentum at end of swing: 14.5 kg*m/s

20. Was total energy conserved?
Energy was not conserved
Friction forces
Partially inelastic collision
Tee might have absorbed some of the energy

21. Were linear and angular momentum conserved?
Momentum was not conserved
Partially inelastic collision
Tee might have absorbed some of the force
Person swinging had momentum as well, which was hard to measure

22. Problems
Angular velocity and momentum of hitter were difficult to calculate, and thus total energy and total momentum calculations may have been off as well
The softball tee absorbed energy as well, making it difficult to determine if more energy may have been conserved had the tee not been there

23. Next Steps
Determine a better way to measure energy and momentum of the hitter
Determine a way to measure the energy and momentum absorbed by the tee
Compare hitting softball off a tee to hitting a pitched ball

24. References http://library.thinkquest.org/11902/physics/momentum.h tml
of-hitting-a-baseball.html
drills.com/physics-of-hitting-a-baseball.html