Baseball problem Impulse-Momentum

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Homework Help Overview

The problem involves analyzing the impulse-momentum relationship for a baseball that is hit by a bat. The baseball's initial and final velocities, along with the angle of deflection, are provided, and the average force applied during the impact is to be determined.

Discussion Character

  • Exploratory, Assumption checking

Approaches and Questions Raised

  • The original poster attempts to calculate the average force using the impulse-momentum equation, breaking down the velocity components and applying them to find the change in momentum. Some participants question the accuracy of the force calculation, suggesting it seems low based on the context of baseball impacts.

Discussion Status

Participants are engaging with the calculations presented, with some offering clarifications on the mass conversion and questioning the force value. There is a recognition of the context of baseball pitch speeds and impact times, which may influence the perceived force results.

Contextual Notes

There is a discussion about the impact time being relatively large for a baseball hit, which may affect the force calculation. Additionally, the comparison to major league baseball scenarios highlights the variability in forces experienced during different types of pitches.

Anarion
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A baseball (4oz .00781 slugs) is thrown at 60 ft/s. After it strikes the bat it is hit at 40 degrees to the initial trajectory (towards third base) and then has a velocity of 120 ft/s. What is the magnitude of the average force applied? T=0.02 sec.



2. F delta T = m delta V



3. Delta Vx= 120 cos 40 - (-60) = 151.9
Delta Vy= 120 sin 40 = 77.13

DeltaV=Square root(1519.9^2+77.1362^2)=170.4

F= .00781*170.4/.02sec =66.5 ft lb

This does not seem right to me. Any help would be appreciated.
 
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A slug is the mass. 4oz/16 =.25/32ft/s^12=0.00781 slugs

Are you sure that is right. The force seems low to me.
 
Anarion said:
A slug is the mass. 4oz/16 =.25/32ft/s^12=0.00781 slugs

Are you sure that is right. The force seems low to me.
Ahh, America! The force is in pounds, not ft-lbs. The impact force does seem low at first, but when you consider the ball is thrown at only 60 ft/sec (about 40 mph, a little league pitch , and less than that of a Wakefield 60 mph knuckle ball, coupled with the fact that the impulse time of 0.02 seconds is 'large', and the ball is not hit squarely back toward the pitcher, then the 66.5 pounds force is reasonable. In a major league baseball game, the speed of the pitch is much faster, and most of all, the impact time of the ball in contact with the bat is much, much smaller, like .001 seconds or less. Thus the impact force could be about 100 times larger, or even more (up to 10,000 pounds in some cases).
 
Thanks for your help!
 

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