Momentum of ball bouncing off crossbar

  • Thread starter Thread starter luffy3san
  • Start date Start date
  • Tags Tags
    Ball Momentum
AI Thread Summary
A soccer ball with a mass of 416 g bounces off a crossbar at a 56.7° angle, with a kinetic energy of 46.9 J. The velocity of the ball after the deflection is calculated to be 15 m/s. The horizontal and vertical components of the momentum are found to be 3.43 kg m/s and 5.22 kg m/s, respectively. However, these values were marked incorrect, prompting a discussion about potential factors like angular momentum, which has not yet been covered in class. Clarification from the instructor is suggested to resolve the discrepancy.
luffy3san
Messages
7
Reaction score
0

Homework Statement



A soccer ball with a mass of 416 g bounces off the crossbar of a goal and is deflected upward at an angle of 56.7° with respect to horizontal. Immediately after the deflection, the kinetic energy of the ball is 46.9 J. What are the vertical and horizontal components of the ball's momentum immediately after striking the crossbar? (Let the horizontal direction be the x-direction and the vertical direction be the y-direction.)

Homework Equations



P = mv
KE = 1/2mv2

The Attempt at a Solution



KEf = 0.5 * m * v2
46.9 = 0.5 * 0.416 * v2
v = 15 m/s

P = mv
Px = 0.416 kg * 15 m/s * cos 56.7 degrees = 3.43 kg m/s
Py = 0.416 kg * 15 m/s * sin 56.7 degrees = 5.22 kg m/s

Any help is appreciated. Thanks.
 
Last edited:
Physics news on Phys.org
You should keep units everywhere, but I don't see where you need help.
 
mfb said:
You should keep units everywhere, but I don't see where you need help.

Ah sorry... I got those two values for the momentum, they were one of the options but was marked as wrong.
 
Last edited:
I get the same answers as you - assuming the ball's not spinning.
 
haruspex said:
I get the same answers as you - assuming the ball's not spinning.

Oh, thanks. We haven't covered angular momentum yet so shouldn't be... i think. I'll have to ask the instructor next class.
 
Thread 'Voltmeter readings for this circuit with switches'
TL;DR Summary: I would like to know the voltmeter readings on the two resistors separately in the picture in the following cases , When one of the keys is closed When both of them are opened (Knowing that the battery has negligible internal resistance) My thoughts for the first case , one of them must be 12 volt while the other is 0 The second case we'll I think both voltmeter readings should be 12 volt since they are both parallel to the battery and they involve the key within what the...
Thread 'Correct statement about a reservoir with an outlet pipe'
The answer to this question is statements (ii) and (iv) are correct. (i) This is FALSE because the speed of water in the tap is greater than speed at the water surface (ii) I don't even understand this statement. What does the "seal" part have to do with water flowing out? Won't the water still flow out through the tap until the tank is empty whether the reservoir is sealed or not? (iii) In my opinion, this statement would be correct. Increasing the gravitational potential energy of the...

Similar threads

Back
Top