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

  • Thread starter Thread starter None_of_the
  • Start date Start date
  • Tags Tags
    Momentum Speed
Join the discussion
Registration is free. Start your own thread to ask a follow-up.
2 replies · 2K views
None_of_the
Messages
6
Reaction score
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
 
Attachments
  • baseball.JPG
    baseball.JPG
    5.9 KB · Views: 478
Last edited:
Physics news on Phys.org
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
 
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 ?