What is the final speed and angle of a ball hit by a baseball bat at 45 degrees?

In summary, the conversation discusses a problem of finding the final speed and angle of a ball that is hit by a baseball bat. The equations used involve conservation of momentum, but this does not apply here due to the bat not being a free body. The conversation also mentions examples in a book that give the final and initial speeds, but the problem at hand is to find the momentum.
  • #1
None_of_the
6
0
Hi,
Sorry for another momentum question I want to be sure.

Homework Statement


A ball who is coming at 180 degree is hit by a baseball bat at 45 degree in the opposite direction. The final speed of the ball and the angle is unknown and this is want we search.

N*S=kg *m/s
I=5 N*S= 5 kg*m/s
Initial ball speed Vo=-30m\s
Bat speed =Vb
Masse M=0.150 Kg


Homework Equations


So I suppose that since the ball is hit at 45 degree
the impulsion will be
5 kg*m/s*cos(45)=the horizontal vector and 5 kg*m/s *cos(45)=the vertical vector


The Attempt at a Solution


5 kg*m/s*cos(45)= 3.5 I
5 kg*m/*sin(45)= 3.5 J
(3.5 I + 3.5J) kg*m/s= 0.150kg(Vb- ( - 30I) )m\s
(23.3 I + 23.3 J )m/s= (Vb+30I) m\s
(-6.7 I + 23.3 J ) m/s = Vb Not in the opposite direction ?
For the final speed = -6.7 I+28J -30I= -36.7I +28J
hmm the baseball bat have hit the ball but not and the right direction, something most be wrong
thank you
 

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  • #2
Conservation of momentum of the bat and ball does not apply here. The reason is that the bat is not a free body. It is connected to the batter who is, in turn, connected to the earth.

AM
 
  • #3
Hmm any ideas how to solve ?
I don't understand Andrew, there are some exemples like this one in my book, but they give the final speed and the initial speed ( the momentum is to find). What is the difference ?
 

1. What is momentum unknow speed?

Momentum unknow speed is a physical quantity that describes the amount of motion an object has. It is calculated by multiplying an object's mass by its velocity. In the context of this question, "unknow speed" refers to the fact that the speed of the object is not known or has not been measured.

2. How is momentum unknow speed different from regular momentum?

Momentum unknow speed and regular momentum are essentially the same concept. The only difference is that in the case of momentum unknow speed, the velocity of the object is not known, while in regular momentum, the velocity is known and can be calculated using the formula p=mv.

3. Why is it important to know an object's momentum unknow speed?

Knowing an object's momentum unknow speed can help us understand how much force is required to change its motion. It also allows us to predict how the object will behave in collisions or interactions with other objects.

4. Can momentum unknow speed be negative?

Yes, momentum unknow speed can be negative. This means that the object is moving in the opposite direction of the chosen reference frame. However, the magnitude of the momentum unknow speed will always be positive.

5. How can momentum unknow speed be calculated if the velocity is not known?

Momentum unknow speed cannot be directly calculated if the velocity is not known. However, if the mass and other variables such as the force or time are known, the velocity can be calculated using the formula p=mv and then used to calculate the momentum unknow speed.

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