Calculating Impulse Magnitude in a 2-Dimensional System

  • Thread starter Thread starter DKPeridot20
  • Start date Start date
  • Tags Tags
    Impulse Magnitude
Click For Summary

Homework Help Overview

The problem involves calculating the magnitude of impulse in a two-dimensional system where a baseball is struck by a bat. The baseball's mass is given, along with the speeds of the pitch and the bat, and the angle at which the ball is hit is specified.

Discussion Character

  • Exploratory, Assumption checking, Problem interpretation

Approaches and Questions Raised

  • The original poster attempts to calculate impulse by determining the change in momentum, but questions arise regarding the interpretation of the speeds involved and the angle of impact. Some participants question whether the speed of 6.258 m/s refers to the bat or the ball after impact, leading to further discussion about the implications of this assumption.

Discussion Status

The discussion is ongoing, with participants exploring different interpretations of the problem's wording and the implications for calculating impulse. There is no explicit consensus on the correct interpretation of the speeds, and some guidance has been offered regarding the need to clarify the velocities involved.

Contextual Notes

Participants note that the problem may be poorly worded and express concern about the lack of information needed to determine the final velocity of the ball after the collision. There is also mention of the potential for typographical errors in the given speeds.

DKPeridot20
Messages
13
Reaction score
0
I'm getting very close, but not quite close enough on this problem:

A baseball is struck by a bat such that it makes an angle of 41 degrees form the direction between the batter and the pitcher. The pitch was thrown at 37.995 m/s. The ball was hit with a speed of 6.258 m/s. What was the magnitude of the impulse in kg*m/s to two sig figs? The baseball has a mass of 0.147 kg.

(I take it to mean the baseball leaves the bat 41 degrees off a line drawn from the pitcher to the batter.)
1) I know that the impulse is equal to the change in momentum. So I said the change in momentum was: mballvball + (-vbat)mball = 4.6651
2) I believed that that gave me the impulse of the ball if it went straight back so I said: 4.6651/cos41 to find the hypotenuse of that x comp I had.

The answer is 6.3 kg*m/s and I get 6.2 kg*m/s.
I did the same problem with different numbers and while their answer was 6.9 mine was 6.0. :frown: What am I doing wrong?
 
Physics news on Phys.org
DKPeridot20 said:
The ball was hit with a speed of 6.258 m/s. ?
Is this supposed to be the speed of the ball after being hit by the bat? (Sounds like more of a "bunt")
 
No. I take it as the speed at which the bat was swung. At the point when it hit the ball, it was going 6.258 m/s. (14 mph)
 
What did you find to be the speed of the ball after the collision with the bat?
 
I didn't find the velocity. I don't see how I can without some kind of distance or time... should I be able to?
 
OK, here' my impression: the question is poorly worded. Without further information, I'm going to have to insist that the 6.258 m/s is the speed of the ball. It's is an absurdly slow speed for either the ball OR bat, so I'm also thinking it was a typo.
If this were the bat's speed, this would not be an easy problem AND it would require the mass of the bat.

OK, so the impulse is the change in momentum which is (mass) times (change in velocity). Can you now find the 2-dimensional value for the vector change in velocity? (delta v)?
 

Similar threads

  • · Replies 4 ·
Replies
4
Views
5K
  • · Replies 6 ·
Replies
6
Views
7K
Replies
1
Views
2K
  • · Replies 10 ·
Replies
10
Views
4K
  • · Replies 19 ·
Replies
19
Views
3K
  • · Replies 2 ·
Replies
2
Views
2K
  • · Replies 2 ·
Replies
2
Views
3K
Replies
13
Views
5K
  • · Replies 5 ·
Replies
5
Views
2K
  • · Replies 13 ·
Replies
13
Views
9K