A 100 g ball with a speed of 5 m/s hits a wall at an angle of 45 degrees. The ball then bounces off the wall at a speed of 5m/s at an angle of 45 degrees. What is the change in the momentum of the ball?
When I look at this problem it seems intuitive to me that the answer should be 0, as the ball's mass remains constant and the speed remains unchanged. However, this is wrong as the velocity changes in this problem. After some calculations, you get around 0.7 kg m/s.
I'm having trouble understanding what this value really represents. How might this answer be useful?
Consider the diagram above. A ball travelling at 5m/s hits the wall and then travels at 5m/s again. What's the change in velocity? Assuming the angle to the wall is 45 degrees.
The ball has the same magnitude of velocity before and after hitting the wall so it doesn't make sense to me to give a numerical value to the change in velocity. The only change is in the direction. However, when you solve for the change in velocity there is a magnitude. What is the representing? Why is there even a magnitude when the speed is the same?
Edit: The magnitude of the velocity and momentum remains the same after collision with the wall. Assuming this is true, then why is the change in momentum 0.7 kg m/s? To me, this is saying there is a change in the magnitude of the momentum which is not true. So what is the value representing? I understand the magnitude remained constant while the direction changed. So why is there a numerical value in the change of momentum?
Links and resources to learn more would be appreciated.